diff --git a/Makefile b/Makefile
index 6537e089b8f7..61abe0e1fcde 100644
--- a/Makefile
+++ b/Makefile
@@ -220,6 +220,14 @@ prepublish:
 
 # --exclude-dependents support is added by .yarn-patches/@lerna/version
 new-version:
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@echo "!!!!!!                                                   !!!!!!"
+	@echo "!!!!!!  Enable the check in proposal-class-static-block  !!!!!!"
+	@echo "!!!!!!                                                   !!!!!!"
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@exit 1
 	git pull --rebase
 	$(YARN) lerna version --exclude-dependents --force-publish=$(FORCE_PUBLISH)
 
diff --git a/packages/babel-core/src/parser/util/missing-plugin-helper.js b/packages/babel-core/src/parser/util/missing-plugin-helper.js
index 5a5f7082f253..aabc8c075d5b 100644
--- a/packages/babel-core/src/parser/util/missing-plugin-helper.js
+++ b/packages/babel-core/src/parser/util/missing-plugin-helper.js
@@ -31,6 +31,16 @@ const pluginNameMap = {
       url: "https://git.io/JvpRG",
     },
   },
+  classStaticBlock: {
+    syntax: {
+      name: "@babel/plugin-syntax-class-static-block",
+      url: "https://git.io/JTLB6",
+    },
+    transform: {
+      name: "@babel/plugin-proposal-class-static-block",
+      url: "https://git.io/JTLBP",
+    },
+  },
   decimal: {
     syntax: {
       name: "@babel/plugin-syntax-decimal",
diff --git a/packages/babel-helper-create-class-features-plugin/src/index.js b/packages/babel-helper-create-class-features-plugin/src/index.js
index d23c12cefdc1..fef48ee705b5 100644
--- a/packages/babel-helper-create-class-features-plugin/src/index.js
+++ b/packages/babel-helper-create-class-features-plugin/src/index.js
@@ -120,6 +120,18 @@ export function createClassFeaturePlugin({
           }
 
           if (!isDecorated) isDecorated = hasOwnDecorators(path.node);
+
+          if (path.isStaticBlock?.()) {
+            throw path.buildCodeFrameError(`Incorrect plugin order, \`@babel/plugin-proposal-class-static-block\` should be placed before class features plugins
+{
+  "plugins": [
+    "@babel/plugin-proposal-class-static-block",
+    "@babel/plugin-proposal-private-property-in-object",
+    "@babel/plugin-proposal-private-methods",
+    "@babel/plugin-proposal-class-properties",
+  ]
+}`);
+          }
         }
 
         if (!props.length && !isDecorated) return;
@@ -188,7 +200,12 @@ export function createClassFeaturePlugin({
       },
 
       PrivateName(path) {
-        if (this.file.get(versionKey) !== version) return;
+        if (
+          this.file.get(versionKey) !== version ||
+          path.parentPath.isPrivate({ key: path.node })
+        ) {
+          return;
+        }
 
         throw path.buildCodeFrameError(`Unknown PrivateName "${path}"`);
       },
diff --git a/packages/babel-helper-module-transforms/package.json b/packages/babel-helper-module-transforms/package.json
index d94542bd7116..1d529e108ed4 100644
--- a/packages/babel-helper-module-transforms/package.json
+++ b/packages/babel-helper-module-transforms/package.json
@@ -20,6 +20,7 @@
     "@babel/helper-simple-access": "workspace:^7.10.4",
     "@babel/helper-split-export-declaration": "workspace:^7.11.0",
     "@babel/template": "workspace:^7.10.4",
+    "@babel/traverse": "workspace:^7.11.5",
     "@babel/types": "workspace:^7.11.0",
     "lodash": "^4.17.19"
   }
diff --git a/packages/babel-helper-module-transforms/src/rewrite-this.js b/packages/babel-helper-module-transforms/src/rewrite-this.js
index cf03366b0ae6..02d96f930ebd 100644
--- a/packages/babel-helper-module-transforms/src/rewrite-this.js
+++ b/packages/babel-helper-module-transforms/src/rewrite-this.js
@@ -1,25 +1,21 @@
-import { skipAllButComputedKey } from "@babel/helper-replace-supers";
+import { environmentVisitor } from "@babel/helper-replace-supers";
+import traverse from "@babel/traverse";
+import * as t from "@babel/types";
+
 export default function rewriteThis(programPath: NodePath) {
   // Rewrite "this" to be "undefined".
-  programPath.traverse(rewriteThisVisitor);
+  traverse(programPath.node, { ...rewriteThisVisitor, noScope: true });
 }
 
 /**
  * A visitor to walk the tree, rewriting all `this` references in the top-level scope to be
- * `undefined`.
+ * `void 0` (undefined).
  */
-const rewriteThisVisitor = {
-  ThisExpression(path) {
-    path.replaceWith(path.scope.buildUndefinedNode());
-  },
-  Function(path) {
-    if (path.isMethod()) skipAllButComputedKey(path);
-    else if (!path.isArrowFunctionExpression()) path.skip();
-  },
-  ClassProperty(path) {
-    skipAllButComputedKey(path);
-  },
-  ClassPrivateProperty(path) {
-    path.skip();
+const rewriteThisVisitor = traverse.visitors.merge([
+  environmentVisitor,
+  {
+    ThisExpression(path) {
+      path.replaceWith(t.unaryExpression("void", t.numericLiteral(0), true));
+    },
   },
-};
+]);
diff --git a/packages/babel-helper-replace-supers/src/index.js b/packages/babel-helper-replace-supers/src/index.js
index 0bf1d50c3d35..32e752de2ffb 100644
--- a/packages/babel-helper-replace-supers/src/index.js
+++ b/packages/babel-helper-replace-supers/src/index.js
@@ -42,8 +42,13 @@ export function skipAllButComputedKey(path: NodePath) {
 }
 
 // environmentVisitor should be used when traversing the whole class and not for specific class elements/methods.
+// For perf reasons, the environmentVisitor will be traversed with `{ noScope: true }`, which means `path.scope` is undefined.
+// Avoid using `path.scope` here
 export const environmentVisitor = {
-  TypeAnnotation(path: NodePath) {
+  // todo (Babel 8): remove StaticBlock brand checks
+  [`${t.StaticBlock ? "StaticBlock|" : ""}ClassPrivateProperty|TypeAnnotation`](
+    path: NodePath,
+  ) {
     path.skip();
   },
 
@@ -55,7 +60,7 @@ export const environmentVisitor = {
     path.skip();
   },
 
-  "Method|ClassProperty|ClassPrivateProperty"(path: NodePath) {
+  "Method|ClassProperty"(path: NodePath) {
     skipAllButComputedKey(path);
   },
 };
diff --git a/packages/babel-plugin-proposal-class-static-block/.npmignore b/packages/babel-plugin-proposal-class-static-block/.npmignore
new file mode 100644
index 000000000000..f9806945836e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/.npmignore
@@ -0,0 +1,3 @@
+src
+test
+*.log
diff --git a/packages/babel-plugin-proposal-class-static-block/README.md b/packages/babel-plugin-proposal-class-static-block/README.md
new file mode 100644
index 000000000000..f1dbec97118c
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/README.md
@@ -0,0 +1,19 @@
+# @babel/plugin-proposal-class-static-block
+
+> Allow transforming of class static blocks
+
+See our website [@babel/plugin-proposal-class-static-block](https://babeljs.io/docs/en/next/babel-plugin-proposal-class-static-block.html) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/plugin-proposal-class-static-block
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/plugin-proposal-class-static-block --dev
+```
diff --git a/packages/babel-plugin-proposal-class-static-block/package.json b/packages/babel-plugin-proposal-class-static-block/package.json
new file mode 100644
index 000000000000..4ba6e6b1a6d6
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/package.json
@@ -0,0 +1,28 @@
+{
+  "name": "@babel/plugin-proposal-class-static-block",
+  "version": "7.11.0",
+  "description": "Allow parsing of class static blocks",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/babel/babel.git",
+    "directory": "packages/babel-plugin-proposal-class-static-block"
+  },
+  "license": "MIT",
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "./lib/index.js",
+  "exports": {
+    ".": "./lib/index.js"
+  },
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "@babel/helper-plugin-utils": "workspace:^7.10.1",
+    "@babel/plugin-syntax-class-static-block": "workspace:^7.11.0"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.12.0"
+  }
+}
diff --git a/packages/babel-plugin-proposal-class-static-block/src/index.js b/packages/babel-plugin-proposal-class-static-block/src/index.js
new file mode 100644
index 000000000000..886bee2dd8b3
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/src/index.js
@@ -0,0 +1,61 @@
+import { declare } from "@babel/helper-plugin-utils";
+import syntaxClassStaticBlock from "@babel/plugin-syntax-class-static-block";
+
+/**
+ * Generate a uid that is not in `denyList`
+ *
+ * @param {*} scope
+ * @param {Set<string>} a deny list that the generated uid should avoid
+ * @returns
+ */
+function generateUid(scope, denyList: Set<string>) {
+  const name = "";
+  let uid;
+  let i = 1;
+  do {
+    uid = scope._generateUid(name, i);
+    i++;
+  } while (denyList.has(uid));
+  return uid;
+}
+
+export default declare(({ types: t, template, assertVersion }) => {
+  // todo: change to ^7.12.0 when it is published
+  assertVersion("^7.11.6");
+
+  return {
+    name: "proposal-class-static-block",
+    inherits: syntaxClassStaticBlock,
+    visitor: {
+      Class(path: NodePath<Class>) {
+        const { scope } = path;
+        const classBody = path.get("body");
+        const privateNames = new Set();
+        let staticBlockPath;
+        for (const path of classBody.get("body")) {
+          if (path.isPrivate()) {
+            privateNames.add(path.get("key.id").node.name);
+          } else if (path.isStaticBlock()) {
+            staticBlockPath = path;
+          }
+        }
+        if (!staticBlockPath) {
+          return;
+        }
+        const staticBlockRef = t.privateName(
+          t.identifier(generateUid(scope, privateNames)),
+        );
+        classBody.pushContainer(
+          "body",
+          t.classPrivateProperty(
+            staticBlockRef,
+            template.expression.ast`(() => { ${staticBlockPath.node.body} })()`,
+            [],
+            /* static */ true,
+          ),
+        );
+        staticBlockPath.remove();
+      },
+    },
+  };
+});
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-binding/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-binding/exec.js
new file mode 100644
index 000000000000..aea35fe5c6ec
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-binding/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = Foo.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/exec.js
new file mode 100644
index 000000000000..a748d4ad1f2e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = this.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/input.js
new file mode 100644
index 000000000000..a748d4ad1f2e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/input.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = this.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/output.js
new file mode 100644
index 000000000000..49139ba432a1
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-declaration/output.js
@@ -0,0 +1,8 @@
+class Foo {
+  static bar = 42;
+  static #_ = (() => {
+    this.foo = this.bar;
+  })();
+}
+
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-expression/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-expression/exec.js
new file mode 100644
index 000000000000..719d9f22eb77
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/class-expression/exec.js
@@ -0,0 +1,6 @@
+class Foo {
+  static {
+    this.foo = 42;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/exec.js
new file mode 100644
index 000000000000..be708dae2b0d
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/exec.js
@@ -0,0 +1,14 @@
+class Foo extends class extends class Base {
+  static {
+    this.qux = 21;
+  }
+} {
+  static {
+    this.bar = 21;
+  }
+} {
+  static {
+    this.foo = this.bar + this.qux;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/input.js
new file mode 100644
index 000000000000..be708dae2b0d
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/input.js
@@ -0,0 +1,14 @@
+class Foo extends class extends class Base {
+  static {
+    this.qux = 21;
+  }
+} {
+  static {
+    this.bar = 21;
+  }
+} {
+  static {
+    this.foo = this.bar + this.qux;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/output.js
new file mode 100644
index 000000000000..ef844d07c994
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/in-class-heritage/output.js
@@ -0,0 +1,15 @@
+class Foo extends class extends class Base {
+  static #_ = (() => {
+    this.qux = 21;
+  })();
+} {
+  static #_ = (() => {
+    this.bar = 21;
+  })();
+} {
+  static #_ = (() => {
+    this.foo = this.bar + this.qux;
+  })();
+}
+
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/multiple-static-initializers/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/multiple-static-initializers/exec.js
new file mode 100644
index 000000000000..657be074147c
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/multiple-static-initializers/exec.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #bar = 21;
+  static {
+    this.foo = this.#bar + this.qux;
+  }
+  static qux = 21;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/exec.js
new file mode 100644
index 000000000000..0de932f8d73a
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/exec.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #_ = 42;
+  // static block can not be tranformed as `#_` here
+  static {
+    this.foo = this.#_;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/input.js
new file mode 100644
index 000000000000..0de932f8d73a
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/input.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #_ = 42;
+  // static block can not be tranformed as `#_` here
+  static {
+    this.foo = this.#_;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/output.js
new file mode 100644
index 000000000000..9f73880d1fc7
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/name-conflict/output.js
@@ -0,0 +1,9 @@
+class Foo {
+  static #_ = 42; // static block can not be tranformed as `#_` here
+
+  static #_2 = (() => {
+    this.foo = this.#_;
+  })();
+}
+
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/non-static/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/non-static/exec.js
new file mode 100644
index 000000000000..1d8845c283de
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/non-static/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  bar = 21;
+  static {
+    this.foo = this.bar;
+  }
+}
+expect(Foo.foo).toBe(undefined);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/options.json b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/options.json
new file mode 100644
index 000000000000..635f1e993525
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/options.json
@@ -0,0 +1,4 @@
+{
+  "plugins": ["proposal-class-static-block", "syntax-class-properties"],
+  "minNodeVersion": "12.0.0"
+}
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/private-elements-access/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/private-elements-access/exec.js
new file mode 100644
index 000000000000..07e589d487dc
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/private-elements-access/exec.js
@@ -0,0 +1,8 @@
+let getFoo;
+class Foo {
+  static #foo = 42;
+  static {
+    getFoo = () => this.#foo;
+  }
+}
+expect(getFoo()).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/super-property/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/super-property/exec.js
new file mode 100644
index 000000000000..637fc8c5f248
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/super-property/exec.js
@@ -0,0 +1,9 @@
+class Foo extends class {
+  static bar = 42;
+} {
+  static bar = 21;
+  static {
+    this.foo = super.bar;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/super-static-block/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/super-static-block/exec.js
new file mode 100644
index 000000000000..866e400fc377
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/class-static-block/super-static-block/exec.js
@@ -0,0 +1,11 @@
+class Foo extends class {
+  static {
+    this.bar = 42;
+  }
+} {
+  static bar = 21;
+  static {
+    this.foo = super.bar;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/exec.js
new file mode 100644
index 000000000000..aea35fe5c6ec
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = Foo.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/input.js
new file mode 100644
index 000000000000..aea35fe5c6ec
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/input.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = Foo.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/output.js
new file mode 100644
index 000000000000..1c8b0fc717a1
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-binding/output.js
@@ -0,0 +1,12 @@
+var _ = babelHelpers.classPrivateFieldLooseKey("_");
+
+class Foo {}
+
+Foo.bar = 42;
+Object.defineProperty(Foo, _, {
+  writable: true,
+  value: (() => {
+    Foo.foo = Foo.bar;
+  })()
+});
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/exec.js
new file mode 100644
index 000000000000..a748d4ad1f2e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = this.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/input.js
new file mode 100644
index 000000000000..a748d4ad1f2e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/input.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = this.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/output.js
new file mode 100644
index 000000000000..1c8b0fc717a1
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-declaration/output.js
@@ -0,0 +1,12 @@
+var _ = babelHelpers.classPrivateFieldLooseKey("_");
+
+class Foo {}
+
+Foo.bar = 42;
+Object.defineProperty(Foo, _, {
+  writable: true,
+  value: (() => {
+    Foo.foo = Foo.bar;
+  })()
+});
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-expression/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-expression/exec.js
new file mode 100644
index 000000000000..719d9f22eb77
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/class-expression/exec.js
@@ -0,0 +1,6 @@
+class Foo {
+  static {
+    this.foo = 42;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/exec.js
new file mode 100644
index 000000000000..be708dae2b0d
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/exec.js
@@ -0,0 +1,14 @@
+class Foo extends class extends class Base {
+  static {
+    this.qux = 21;
+  }
+} {
+  static {
+    this.bar = 21;
+  }
+} {
+  static {
+    this.foo = this.bar + this.qux;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/input.js
new file mode 100644
index 000000000000..be708dae2b0d
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/input.js
@@ -0,0 +1,14 @@
+class Foo extends class extends class Base {
+  static {
+    this.qux = 21;
+  }
+} {
+  static {
+    this.bar = 21;
+  }
+} {
+  static {
+    this.foo = this.bar + this.qux;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/output.js
new file mode 100644
index 000000000000..790f057648d3
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/in-class-heritage/output.js
@@ -0,0 +1,23 @@
+var _class, _2, _temp, _class2, _3, _temp2;
+
+var _ = babelHelpers.classPrivateFieldLooseKey("_");
+
+class Foo extends (_temp = (_2 = babelHelpers.classPrivateFieldLooseKey("_"), _class = class extends (_temp2 = (_3 = babelHelpers.classPrivateFieldLooseKey("_"), _class2 = class Base {}), Object.defineProperty(_class2, _3, {
+  writable: true,
+  value: (() => {
+    _class2.qux = 21;
+  })()
+}), _temp2) {}), Object.defineProperty(_class, _2, {
+  writable: true,
+  value: (() => {
+    _class.bar = 21;
+  })()
+}), _temp) {}
+
+Object.defineProperty(Foo, _, {
+  writable: true,
+  value: (() => {
+    Foo.foo = Foo.bar + Foo.qux;
+  })()
+});
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/multiple-static-initializers/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/multiple-static-initializers/exec.js
new file mode 100644
index 000000000000..657be074147c
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/multiple-static-initializers/exec.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #bar = 21;
+  static {
+    this.foo = this.#bar + this.qux;
+  }
+  static qux = 21;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/exec.js
new file mode 100644
index 000000000000..0de932f8d73a
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/exec.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #_ = 42;
+  // static block can not be tranformed as `#_` here
+  static {
+    this.foo = this.#_;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/input.js
new file mode 100644
index 000000000000..0de932f8d73a
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/input.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #_ = 42;
+  // static block can not be tranformed as `#_` here
+  static {
+    this.foo = this.#_;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/output.js
new file mode 100644
index 000000000000..9782eba3fab9
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/name-conflict/output.js
@@ -0,0 +1,17 @@
+var _ = babelHelpers.classPrivateFieldLooseKey("_");
+
+var _2 = babelHelpers.classPrivateFieldLooseKey("_2");
+
+class Foo {}
+
+Object.defineProperty(Foo, _, {
+  writable: true,
+  value: 42
+});
+Object.defineProperty(Foo, _2, {
+  writable: true,
+  value: (() => {
+    Foo.foo = babelHelpers.classPrivateFieldLooseBase(Foo, _)[_];
+  })()
+});
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/non-static/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/non-static/exec.js
new file mode 100644
index 000000000000..1d8845c283de
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/non-static/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  bar = 21;
+  static {
+    this.foo = this.bar;
+  }
+}
+expect(Foo.foo).toBe(undefined);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/options.json b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/options.json
new file mode 100644
index 000000000000..0c80ad46dc94
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/options.json
@@ -0,0 +1,9 @@
+{
+  "plugins": [
+    "proposal-class-static-block",
+    ["proposal-private-property-in-object", { "loose": true }],
+    ["proposal-private-methods", { "loose": true }],
+    ["proposal-class-properties", { "loose": true }],
+    "external-helpers"
+  ]
+}
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-elements-access/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-elements-access/exec.js
new file mode 100644
index 000000000000..07e589d487dc
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-elements-access/exec.js
@@ -0,0 +1,8 @@
+let getFoo;
+class Foo {
+  static #foo = 42;
+  static {
+    getFoo = () => this.#foo;
+  }
+}
+expect(getFoo()).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-in/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-in/exec.js
new file mode 100644
index 000000000000..10cd0427cd2e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-in/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  static #bar = 21;
+  static {
+    this.foo = #bar in this;
+  }
+}
+expect(Foo.foo).toBe(true);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-methods-access/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-methods-access/exec.js
new file mode 100644
index 000000000000..8981afcf541e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/private-methods-access/exec.js
@@ -0,0 +1,8 @@
+let getFoo;
+class Foo {
+  static #foo() { return 42 };
+  static {
+    getFoo = () => this.#foo();
+  }
+}
+expect(getFoo()).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-property/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-property/exec.js
new file mode 100644
index 000000000000..637fc8c5f248
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-property/exec.js
@@ -0,0 +1,9 @@
+class Foo extends class {
+  static bar = 42;
+} {
+  static bar = 21;
+  static {
+    this.foo = super.bar;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/exec.js
new file mode 100644
index 000000000000..866e400fc377
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/exec.js
@@ -0,0 +1,11 @@
+class Foo extends class {
+  static {
+    this.bar = 42;
+  }
+} {
+  static bar = 21;
+  static {
+    this.foo = super.bar;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/input.js
new file mode 100644
index 000000000000..866e400fc377
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/input.js
@@ -0,0 +1,11 @@
+class Foo extends class {
+  static {
+    this.bar = 42;
+  }
+} {
+  static bar = 21;
+  static {
+    this.foo = super.bar;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/output.js
new file mode 100644
index 000000000000..384a75d00dbe
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration-loose/super-static-block/output.js
@@ -0,0 +1,26 @@
+var _class, _2, _temp;
+
+var _ = babelHelpers.classPrivateFieldLooseKey("_");
+
+class Foo extends (_temp = (_2 = babelHelpers.classPrivateFieldLooseKey("_"), _class = class {}), Object.defineProperty(_class, _2, {
+  writable: true,
+  value: (() => {
+    _class.bar = 42;
+  })()
+}), _temp) {}
+
+Foo.bar = 21;
+Object.defineProperty(Foo, _, {
+  writable: true,
+  value: (() => {
+    var _class2, _3, _temp2;
+
+    Foo.foo = (_temp2 = (_3 = babelHelpers.classPrivateFieldLooseKey("_"), _class2 = class {}), Object.defineProperty(_class2, _3, {
+      writable: true,
+      value: (() => {
+        _class2.bar = 42;
+      })()
+    }), _temp2).bar;
+  })()
+});
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/exec.js
new file mode 100644
index 000000000000..aea35fe5c6ec
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = Foo.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/input.js
new file mode 100644
index 000000000000..aea35fe5c6ec
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/input.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = Foo.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/output.js
new file mode 100644
index 000000000000..810eeba965a4
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-binding/output.js
@@ -0,0 +1,10 @@
+class Foo {}
+
+babelHelpers.defineProperty(Foo, "bar", 42);
+var _ = {
+  writable: true,
+  value: (() => {
+    Foo.foo = Foo.bar;
+  })()
+};
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/exec.js
new file mode 100644
index 000000000000..a748d4ad1f2e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = this.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/input.js
new file mode 100644
index 000000000000..a748d4ad1f2e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/input.js
@@ -0,0 +1,7 @@
+class Foo {
+  static {
+    this.foo = this.bar;
+  }
+  static bar = 42;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/output.js
new file mode 100644
index 000000000000..810eeba965a4
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-declaration/output.js
@@ -0,0 +1,10 @@
+class Foo {}
+
+babelHelpers.defineProperty(Foo, "bar", 42);
+var _ = {
+  writable: true,
+  value: (() => {
+    Foo.foo = Foo.bar;
+  })()
+};
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-expression/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-expression/exec.js
new file mode 100644
index 000000000000..719d9f22eb77
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/class-expression/exec.js
@@ -0,0 +1,6 @@
+class Foo {
+  static {
+    this.foo = 42;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/exec.js
new file mode 100644
index 000000000000..be708dae2b0d
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/exec.js
@@ -0,0 +1,14 @@
+class Foo extends class extends class Base {
+  static {
+    this.qux = 21;
+  }
+} {
+  static {
+    this.bar = 21;
+  }
+} {
+  static {
+    this.foo = this.bar + this.qux;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/input.js
new file mode 100644
index 000000000000..be708dae2b0d
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/input.js
@@ -0,0 +1,14 @@
+class Foo extends class extends class Base {
+  static {
+    this.qux = 21;
+  }
+} {
+  static {
+    this.bar = 21;
+  }
+} {
+  static {
+    this.foo = this.bar + this.qux;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/output.js
new file mode 100644
index 000000000000..ed5682822e11
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/in-class-heritage/output.js
@@ -0,0 +1,21 @@
+var _class, _temp, _2, _class2, _temp2, _3;
+
+class Foo extends (_temp = _class = class extends (_temp2 = _class2 = class Base {}, _3 = {
+  writable: true,
+  value: (() => {
+    _class2.qux = 21;
+  })()
+}, _temp2) {}, _2 = {
+  writable: true,
+  value: (() => {
+    _class.bar = 21;
+  })()
+}, _temp) {}
+
+var _ = {
+  writable: true,
+  value: (() => {
+    Foo.foo = Foo.bar + Foo.qux;
+  })()
+};
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/multiple-static-initializers/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/multiple-static-initializers/exec.js
new file mode 100644
index 000000000000..657be074147c
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/multiple-static-initializers/exec.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #bar = 21;
+  static {
+    this.foo = this.#bar + this.qux;
+  }
+  static qux = 21;
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/exec.js
new file mode 100644
index 000000000000..0de932f8d73a
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/exec.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #_ = 42;
+  // static block can not be tranformed as `#_` here
+  static {
+    this.foo = this.#_;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/input.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/input.js
new file mode 100644
index 000000000000..0de932f8d73a
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/input.js
@@ -0,0 +1,8 @@
+class Foo {
+  static #_ = 42;
+  // static block can not be tranformed as `#_` here
+  static {
+    this.foo = this.#_;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/output.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/output.js
new file mode 100644
index 000000000000..afd334165910
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/name-conflict/output.js
@@ -0,0 +1,15 @@
+function _classStaticPrivateFieldSpecGet(receiver, classConstructor, descriptor) { if (receiver !== classConstructor) { throw new TypeError("Private static access of wrong provenance"); } if (descriptor.get) { return descriptor.get.call(receiver); } return descriptor.value; }
+
+class Foo {}
+
+var _ = {
+  writable: true,
+  value: 42
+};
+var _2 = {
+  writable: true,
+  value: (() => {
+    Foo.foo = _classStaticPrivateFieldSpecGet(Foo, Foo, _);
+  })()
+};
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/non-static/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/non-static/exec.js
new file mode 100644
index 000000000000..1d8845c283de
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/non-static/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  bar = 21;
+  static {
+    this.foo = this.bar;
+  }
+}
+expect(Foo.foo).toBe(undefined);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/options.json b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/options.json
new file mode 100644
index 000000000000..6acec4a94e0a
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/options.json
@@ -0,0 +1,9 @@
+{
+  "plugins": [
+    "proposal-class-static-block",
+    "proposal-private-property-in-object",
+    "proposal-private-methods",
+    "proposal-class-properties",
+    "external-helpers"
+  ]
+}
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-elements-access/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-elements-access/exec.js
new file mode 100644
index 000000000000..07e589d487dc
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-elements-access/exec.js
@@ -0,0 +1,8 @@
+let getFoo;
+class Foo {
+  static #foo = 42;
+  static {
+    getFoo = () => this.#foo;
+  }
+}
+expect(getFoo()).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-in/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-in/exec.js
new file mode 100644
index 000000000000..10cd0427cd2e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-in/exec.js
@@ -0,0 +1,7 @@
+class Foo {
+  static #bar = 21;
+  static {
+    this.foo = #bar in this;
+  }
+}
+expect(Foo.foo).toBe(true);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-methods-access/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-methods-access/exec.js
new file mode 100644
index 000000000000..8981afcf541e
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/private-methods-access/exec.js
@@ -0,0 +1,8 @@
+let getFoo;
+class Foo {
+  static #foo() { return 42 };
+  static {
+    getFoo = () => this.#foo();
+  }
+}
+expect(getFoo()).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/super-property/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/super-property/exec.js
new file mode 100644
index 000000000000..637fc8c5f248
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/super-property/exec.js
@@ -0,0 +1,9 @@
+class Foo extends class {
+  static bar = 42;
+} {
+  static bar = 21;
+  static {
+    this.foo = super.bar;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/super-static-block/exec.js b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/super-static-block/exec.js
new file mode 100644
index 000000000000..866e400fc377
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/integration/super-static-block/exec.js
@@ -0,0 +1,11 @@
+class Foo extends class {
+  static {
+    this.bar = 42;
+  }
+} {
+  static bar = 21;
+  static {
+    this.foo = super.bar;
+  }
+}
+expect(Foo.foo).toBe(42);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/fixtures/options.json b/packages/babel-plugin-proposal-class-static-block/test/fixtures/options.json
new file mode 100644
index 000000000000..34b2bd61b0d7
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/fixtures/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["proposal-class-static-block"]
+}
diff --git a/packages/babel-plugin-proposal-class-static-block/test/index.js b/packages/babel-plugin-proposal-class-static-block/test/index.js
new file mode 100644
index 000000000000..1b534b8fc64a
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/index.js
@@ -0,0 +1,3 @@
+import runner from "@babel/helper-plugin-test-runner";
+
+runner(__dirname);
diff --git a/packages/babel-plugin-proposal-class-static-block/test/plugin-ordering.test.js b/packages/babel-plugin-proposal-class-static-block/test/plugin-ordering.test.js
new file mode 100644
index 000000000000..675e970382ac
--- /dev/null
+++ b/packages/babel-plugin-proposal-class-static-block/test/plugin-ordering.test.js
@@ -0,0 +1,41 @@
+import * as babel from "@babel/core";
+import proposalClassStaticBlock from "../lib/index.js";
+
+describe("plugin ordering", () => {
+  it("should throw when @babel/plugin-proposal-class-static-block is after class features plugin", () => {
+    const source = `class Foo {
+  static {
+    this.foo = Foo.bar;
+  }
+  static bar = 42;
+}
+`;
+    expect(() => {
+      babel.transform(source, {
+        filename: "example.js",
+        highlightCode: false,
+        configFile: false,
+        babelrc: false,
+        plugins: [
+          "@babel/plugin-proposal-class-properties",
+          proposalClassStaticBlock,
+        ],
+      });
+    })
+      .toThrow(`Incorrect plugin order, \`@babel/plugin-proposal-class-static-block\` should be placed before class features plugins
+{
+  "plugins": [
+    "@babel/plugin-proposal-class-static-block",
+    "@babel/plugin-proposal-private-property-in-object",
+    "@babel/plugin-proposal-private-methods",
+    "@babel/plugin-proposal-class-properties",
+  ]
+}
+  1 | class Foo {
+> 2 |   static {
+    |   ^
+  3 |     this.foo = Foo.bar;
+  4 |   }
+  5 |   static bar = 42;`);
+  });
+});
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/input.mjs b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/input.mjs
new file mode 100644
index 000000000000..eace310e6dfa
--- /dev/null
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/input.mjs
@@ -0,0 +1,5 @@
+class foo {
+    static {
+        this // should not be replaced by undefined
+    }
+}
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/options.json b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/options.json
new file mode 100644
index 000000000000..b14a64139e69
--- /dev/null
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-modules-commonjs", "syntax-class-static-block"]
+}
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/output.js
new file mode 100644
index 000000000000..cdee4cf680f2
--- /dev/null
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/misc/class-static-block/output.js
@@ -0,0 +1,8 @@
+"use strict";
+
+class foo {
+  static {
+    this; // should not be replaced by undefined
+
+  }
+}
diff --git a/packages/babel-standalone/package.json b/packages/babel-standalone/package.json
index e70f848f058d..ce211b9a3931 100644
--- a/packages/babel-standalone/package.json
+++ b/packages/babel-standalone/package.json
@@ -13,6 +13,7 @@
     "@babel/plugin-external-helpers": "workspace:^7.10.4",
     "@babel/plugin-proposal-async-generator-functions": "workspace:^7.10.5",
     "@babel/plugin-proposal-class-properties": "workspace:^7.10.4",
+    "@babel/plugin-proposal-class-static-block": "workspace:^7.11.0",
     "@babel/plugin-proposal-decorators": "workspace:^7.10.5",
     "@babel/plugin-proposal-do-expressions": "workspace:^7.10.4",
     "@babel/plugin-proposal-dynamic-import": "workspace:^7.10.4",
@@ -34,6 +35,7 @@
     "@babel/plugin-proposal-unicode-property-regex": "workspace:^7.10.4",
     "@babel/plugin-syntax-async-generators": "^7.8.0",
     "@babel/plugin-syntax-class-properties": "workspace:^7.10.4",
+    "@babel/plugin-syntax-class-static-block": "workspace:^7.11.0",
     "@babel/plugin-syntax-decimal": "workspace:^7.11.0",
     "@babel/plugin-syntax-decorators": "workspace:^7.10.4",
     "@babel/plugin-syntax-do-expressions": "workspace:^7.10.4",
diff --git a/packages/babel-standalone/scripts/pluginConfig.json b/packages/babel-standalone/scripts/pluginConfig.json
index 2b2c3f3a4219..326d74c0c335 100644
--- a/packages/babel-standalone/scripts/pluginConfig.json
+++ b/packages/babel-standalone/scripts/pluginConfig.json
@@ -2,6 +2,7 @@
   "external-helpers",
   "syntax-async-generators",
   "syntax-class-properties",
+  "syntax-class-static-block",
   "syntax-decimal",
   "syntax-decorators",
   "syntax-do-expressions",
@@ -20,6 +21,7 @@
   "syntax-typescript",
   "proposal-async-generator-functions",
   "proposal-class-properties",
+  "proposal-class-static-block",
   "proposal-decorators",
   "proposal-do-expressions",
   "proposal-dynamic-import",
diff --git a/packages/babel-standalone/src/generated/plugins.js b/packages/babel-standalone/src/generated/plugins.js
index 757d39e53cc9..90d61b6b8139 100644
--- a/packages/babel-standalone/src/generated/plugins.js
+++ b/packages/babel-standalone/src/generated/plugins.js
@@ -6,6 +6,7 @@
 import externalHelpers from "@babel/plugin-external-helpers";
 import syntaxAsyncGenerators from "@babel/plugin-syntax-async-generators";
 import syntaxClassProperties from "@babel/plugin-syntax-class-properties";
+import syntaxClassStaticBlock from "@babel/plugin-syntax-class-static-block";
 import syntaxDecimal from "@babel/plugin-syntax-decimal";
 import syntaxDecorators from "@babel/plugin-syntax-decorators";
 import syntaxDoExpressions from "@babel/plugin-syntax-do-expressions";
@@ -24,6 +25,7 @@ import syntaxTopLevelAwait from "@babel/plugin-syntax-top-level-await";
 import syntaxTypescript from "@babel/plugin-syntax-typescript";
 import proposalAsyncGeneratorFunctions from "@babel/plugin-proposal-async-generator-functions";
 import proposalClassProperties from "@babel/plugin-proposal-class-properties";
+import proposalClassStaticBlock from "@babel/plugin-proposal-class-static-block";
 import proposalDecorators from "@babel/plugin-proposal-decorators";
 import proposalDoExpressions from "@babel/plugin-proposal-do-expressions";
 import proposalDynamicImport from "@babel/plugin-proposal-dynamic-import";
@@ -99,6 +101,7 @@ export {
   externalHelpers,
   syntaxAsyncGenerators,
   syntaxClassProperties,
+  syntaxClassStaticBlock,
   syntaxDecimal,
   syntaxDecorators,
   syntaxDoExpressions,
@@ -117,6 +120,7 @@ export {
   syntaxTypescript,
   proposalAsyncGeneratorFunctions,
   proposalClassProperties,
+  proposalClassStaticBlock,
   proposalDecorators,
   proposalDoExpressions,
   proposalDynamicImport,
@@ -193,6 +197,7 @@ export const all = {
   "external-helpers": externalHelpers,
   "syntax-async-generators": syntaxAsyncGenerators,
   "syntax-class-properties": syntaxClassProperties,
+  "syntax-class-static-block": syntaxClassStaticBlock,
   "syntax-decimal": syntaxDecimal,
   "syntax-decorators": syntaxDecorators,
   "syntax-do-expressions": syntaxDoExpressions,
@@ -211,6 +216,7 @@ export const all = {
   "syntax-typescript": syntaxTypescript,
   "proposal-async-generator-functions": proposalAsyncGeneratorFunctions,
   "proposal-class-properties": proposalClassProperties,
+  "proposal-class-static-block": proposalClassStaticBlock,
   "proposal-decorators": proposalDecorators,
   "proposal-do-expressions": proposalDoExpressions,
   "proposal-dynamic-import": proposalDynamicImport,
diff --git a/packages/babel-standalone/src/preset-stage-1.js b/packages/babel-standalone/src/preset-stage-1.js
index 0e0cd18c138c..4b40aaf96f79 100644
--- a/packages/babel-standalone/src/preset-stage-1.js
+++ b/packages/babel-standalone/src/preset-stage-1.js
@@ -29,7 +29,6 @@ export default (_: any, opts: Object = {}) => {
       [babelPlugins.syntaxRecordAndTuple, { syntaxType: recordAndTupleSyntax }],
       babelPlugins.proposalExportDefaultFrom,
       [babelPlugins.proposalPipelineOperator, { proposal: pipelineProposal }],
-      babelPlugins.proposalPrivatePropertyInObject,
       babelPlugins.proposalDoExpressions,
     ],
   };
diff --git a/packages/babel-standalone/src/preset-stage-2.js b/packages/babel-standalone/src/preset-stage-2.js
index 7df7c1492346..f0eff5756e0a 100644
--- a/packages/babel-standalone/src/preset-stage-2.js
+++ b/packages/babel-standalone/src/preset-stage-2.js
@@ -13,11 +13,13 @@ export default (_: any, opts: Object = {}) => {
   return {
     presets: [[presetStage3, { loose, useBuiltIns }]],
     plugins: [
+      babelPlugins.proposalClassStaticBlock,
       [
         babelPlugins.proposalDecorators,
         { legacy: decoratorsLegacy, decoratorsBeforeExport },
       ],
       babelPlugins.proposalFunctionSent,
+      babelPlugins.proposalPrivatePropertyInObject,
       babelPlugins.proposalThrowExpressions,
     ],
   };
diff --git a/packages/babel-traverse/src/scope/index.js b/packages/babel-traverse/src/scope/index.js
index 321db204ccc4..671f1b34751a 100644
--- a/packages/babel-traverse/src/scope/index.js
+++ b/packages/babel-traverse/src/scope/index.js
@@ -368,7 +368,7 @@ export default class Scope {
       .replace(/[0-9]+$/g, "");
 
     let uid;
-    let i = 0;
+    let i = 1;
     do {
       uid = this._generateUid(name, i);
       i++;
diff --git a/packages/babel-types/src/definitions/experimental.js b/packages/babel-types/src/definitions/experimental.js
index d9e0b9879a8b..e11581704963 100644
--- a/packages/babel-types/src/definitions/experimental.js
+++ b/packages/babel-types/src/definitions/experimental.js
@@ -108,7 +108,7 @@ defineType("PipelinePrimaryTopicReference", {
 
 defineType("ClassPrivateProperty", {
   visitor: ["key", "value", "decorators"],
-  builder: ["key", "value", "decorators"],
+  builder: ["key", "value", "decorators", "static"],
   aliases: ["Property", "Private"],
   fields: {
     key: {
diff --git a/yarn.lock b/yarn.lock
index b3bec718c577..20531c4a3cc6 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -601,6 +601,7 @@ __metadata:
     "@babel/helper-simple-access": "workspace:^7.10.4"
     "@babel/helper-split-export-declaration": "workspace:^7.11.0"
     "@babel/template": "workspace:^7.10.4"
+    "@babel/traverse": "workspace:^7.11.5"
     "@babel/types": "workspace:^7.11.0"
     lodash: ^4.17.19
   languageName: unknown
@@ -1004,6 +1005,17 @@ __metadata:
   languageName: unknown
   linkType: soft
 
+"@babel/plugin-proposal-class-static-block@workspace:^7.11.0, @babel/plugin-proposal-class-static-block@workspace:packages/babel-plugin-proposal-class-static-block":
+  version: 0.0.0-use.local
+  resolution: "@babel/plugin-proposal-class-static-block@workspace:packages/babel-plugin-proposal-class-static-block"
+  dependencies:
+    "@babel/helper-plugin-utils": "workspace:^7.10.1"
+    "@babel/plugin-syntax-class-static-block": "workspace:^7.11.0"
+  peerDependencies:
+    "@babel/core": ^7.12.0
+  languageName: unknown
+  linkType: soft
+
 "@babel/plugin-proposal-decorators@workspace:^7.10.4, @babel/plugin-proposal-decorators@workspace:^7.10.5, @babel/plugin-proposal-decorators@workspace:packages/babel-plugin-proposal-decorators":
   version: 0.0.0-use.local
   resolution: "@babel/plugin-proposal-decorators@workspace:packages/babel-plugin-proposal-decorators"
@@ -1449,7 +1461,7 @@ __metadata:
   languageName: unknown
   linkType: soft
 
-"@babel/plugin-syntax-class-static-block@workspace:packages/babel-plugin-syntax-class-static-block":
+"@babel/plugin-syntax-class-static-block@workspace:^7.11.0, @babel/plugin-syntax-class-static-block@workspace:packages/babel-plugin-syntax-class-static-block":
   version: 0.0.0-use.local
   resolution: "@babel/plugin-syntax-class-static-block@workspace:packages/babel-plugin-syntax-class-static-block"
   dependencies:
@@ -3204,6 +3216,7 @@ __metadata:
     "@babel/plugin-external-helpers": "workspace:^7.10.4"
     "@babel/plugin-proposal-async-generator-functions": "workspace:^7.10.5"
     "@babel/plugin-proposal-class-properties": "workspace:^7.10.4"
+    "@babel/plugin-proposal-class-static-block": "workspace:^7.11.0"
     "@babel/plugin-proposal-decorators": "workspace:^7.10.5"
     "@babel/plugin-proposal-do-expressions": "workspace:^7.10.4"
     "@babel/plugin-proposal-dynamic-import": "workspace:^7.10.4"
@@ -3225,6 +3238,7 @@ __metadata:
     "@babel/plugin-proposal-unicode-property-regex": "workspace:^7.10.4"
     "@babel/plugin-syntax-async-generators": ^7.8.0
     "@babel/plugin-syntax-class-properties": "workspace:^7.10.4"
+    "@babel/plugin-syntax-class-static-block": "workspace:^7.11.0"
     "@babel/plugin-syntax-decimal": "workspace:^7.11.0"
     "@babel/plugin-syntax-decorators": "workspace:^7.10.4"
     "@babel/plugin-syntax-do-expressions": "workspace:^7.10.4"