diff --git a/parser.go b/parser.go
index 4f8810e..bebf0af 100644
--- a/parser.go
+++ b/parser.go
@@ -13,6 +13,10 @@ import (
 type parser struct {
 	s string // the source text
 	i int    // the current position
+
+	// if `false`, parsing a pseudo-element
+	// returns an error.
+	acceptPseudoElements bool
 }
 
 // parseEscape parses a backslash escape.
@@ -422,17 +426,25 @@ var errExpectedParenthesis = errors.New("expected '(' but didn't find it")
 var errExpectedClosingParenthesis = errors.New("expected ')' but didn't find it")
 var errUnmatchedParenthesis = errors.New("unmatched '('")
 
-// parsePseudoclassSelector parses a pseudoclass selector like :not(p)
-func (p *parser) parsePseudoclassSelector() (out Sel, err error) {
+// parsePseudoclassSelector parses a pseudoclass selector like :not(p) or a pseudo-element
+// For backwards compatibility, both ':' and '::' prefix are allowed for pseudo-elements.
+// https://drafts.csswg.org/selectors-3/#pseudo-elements
+// Returning a nil `Sel` (and a nil `error`) means we found a pseudo-element.
+func (p *parser) parsePseudoclassSelector() (out Sel, pseudoElement string, err error) {
 	if p.i >= len(p.s) {
-		return nil, fmt.Errorf("expected pseudoclass selector (:pseudoclass), found EOF instead")
+		return nil, "", fmt.Errorf("expected pseudoclass selector (:pseudoclass), found EOF instead")
 	}
 	if p.s[p.i] != ':' {
-		return nil, fmt.Errorf("expected attribute selector (:pseudoclass), found '%c' instead", p.s[p.i])
+		return nil, "", fmt.Errorf("expected attribute selector (:pseudoclass), found '%c' instead", p.s[p.i])
 	}
 
 	p.i++
+	var mustBePseudoElement bool
+	if p.i >= len(p.s) {
+		return nil, "", fmt.Errorf("got empty pseudoclass (or pseudoelement)")
+	}
 	if p.s[p.i] == ':' { // we found a pseudo-element
+		mustBePseudoElement = true
 		p.i++
 	}
 
@@ -441,27 +453,33 @@ func (p *parser) parsePseudoclassSelector() (out Sel, err error) {
 		return
 	}
 	name = toLowerASCII(name)
+	if mustBePseudoElement && (name != "after" && name != "backdrop" && name != "before" &&
+		name != "cue" && name != "first-letter" && name != "first-line" && name != "grammar-error" &&
+		name != "marker" && name != "placeholder" && name != "selection" && name != "spelling-error") {
+		return out, "", fmt.Errorf("unknown pseudoelement :%s", name)
+	}
+
 	switch name {
 	case "not", "has", "haschild":
 		if !p.consumeParenthesis() {
-			return out, errExpectedParenthesis
+			return out, "", errExpectedParenthesis
 		}
 		sel, parseErr := p.parseSelectorGroup()
 		if parseErr != nil {
-			return out, parseErr
+			return out, "", parseErr
 		}
 		if !p.consumeClosingParenthesis() {
-			return out, errExpectedClosingParenthesis
+			return out, "", errExpectedClosingParenthesis
 		}
 
 		out = relativePseudoClassSelector{name: name, match: sel}
 
 	case "contains", "containsown":
 		if !p.consumeParenthesis() {
-			return out, errExpectedParenthesis
+			return out, "", errExpectedParenthesis
 		}
 		if p.i == len(p.s) {
-			return out, errUnmatchedParenthesis
+			return out, "", errUnmatchedParenthesis
 		}
 		var val string
 		switch p.s[p.i] {
@@ -471,46 +489,46 @@ func (p *parser) parsePseudoclassSelector() (out Sel, err error) {
 			val, err = p.parseIdentifier()
 		}
 		if err != nil {
-			return out, err
+			return out, "", err
 		}
 		val = strings.ToLower(val)
 		p.skipWhitespace()
 		if p.i >= len(p.s) {
-			return out, errors.New("unexpected EOF in pseudo selector")
+			return out, "", errors.New("unexpected EOF in pseudo selector")
 		}
 		if !p.consumeClosingParenthesis() {
-			return out, errExpectedClosingParenthesis
+			return out, "", errExpectedClosingParenthesis
 		}
 
 		out = containsPseudoClassSelector{own: name == "containsown", value: val}
 
 	case "matches", "matchesown":
 		if !p.consumeParenthesis() {
-			return out, errExpectedParenthesis
+			return out, "", errExpectedParenthesis
 		}
 		rx, err := p.parseRegex()
 		if err != nil {
-			return out, err
+			return out, "", err
 		}
 		if p.i >= len(p.s) {
-			return out, errors.New("unexpected EOF in pseudo selector")
+			return out, "", errors.New("unexpected EOF in pseudo selector")
 		}
 		if !p.consumeClosingParenthesis() {
-			return out, errExpectedClosingParenthesis
+			return out, "", errExpectedClosingParenthesis
 		}
 
 		out = regexpPseudoClassSelector{own: name == "matchesown", regexp: rx}
 
 	case "nth-child", "nth-last-child", "nth-of-type", "nth-last-of-type":
 		if !p.consumeParenthesis() {
-			return out, errExpectedParenthesis
+			return out, "", errExpectedParenthesis
 		}
 		a, b, err := p.parseNth()
 		if err != nil {
-			return out, err
+			return out, "", err
 		}
 		if !p.consumeClosingParenthesis() {
-			return out, errExpectedClosingParenthesis
+			return out, "", errExpectedClosingParenthesis
 		}
 		last := name == "nth-last-child" || name == "nth-last-of-type"
 		ofType := name == "nth-of-type" || name == "nth-last-of-type"
@@ -535,9 +553,9 @@ func (p *parser) parsePseudoclassSelector() (out Sel, err error) {
 	case "root":
 		out = rootPseudoClassSelector{}
 	case "after", "backdrop", "before", "cue", "first-letter", "first-line", "grammar-error", "marker", "placeholder", "selection", "spelling-error":
-		return out, errors.New("pseudo-elements are not yet supported")
+		return nil, name, nil
 	default:
-		return out, fmt.Errorf("unknown pseudoclass or pseudoelement :%s", name)
+		return out, "", fmt.Errorf("unknown pseudoclass or pseudoelement :%s", name)
 	}
 	return
 }
@@ -706,11 +724,13 @@ func (p *parser) parseSimpleSelectorSequence() (Sel, error) {
 		selectors = append(selectors, r)
 	}
 
+	var pseudoElement string
 loop:
 	for p.i < len(p.s) {
 		var (
-			ns  Sel
-			err error
+			ns               Sel
+			newPseudoElement string
+			err              error
 		)
 		switch p.s[p.i] {
 		case '#':
@@ -720,20 +740,37 @@ loop:
 		case '[':
 			ns, err = p.parseAttributeSelector()
 		case ':':
-			ns, err = p.parsePseudoclassSelector()
+			ns, newPseudoElement, err = p.parsePseudoclassSelector()
 		default:
 			break loop
 		}
 		if err != nil {
 			return nil, err
 		}
+		// From https://drafts.csswg.org/selectors-3/#pseudo-elements :
+		// "Only one pseudo-element may appear per selector, and if present
+		// it must appear after the sequence of simple selectors that
+		// represents the subjects of the selector.""
+		if ns == nil { // we found a pseudo-element
+			if pseudoElement != "" {
+				return nil, fmt.Errorf("only one pseudo-element is accepted per selector, got %s and %s", pseudoElement, newPseudoElement)
+			}
+			if !p.acceptPseudoElements {
+				return nil, fmt.Errorf("pseudo-element %s found, but pseudo-elements support is disabled", newPseudoElement)
+			}
+			pseudoElement = newPseudoElement
+		} else {
+			if pseudoElement != "" {
+				return nil, fmt.Errorf("pseudo-element %s must be at the end of selector", pseudoElement)
+			}
+			selectors = append(selectors, ns)
+		}
 
-		selectors = append(selectors, ns)
 	}
-	if len(selectors) == 1 { // no need wrap the selectors in compoundSelector
+	if len(selectors) == 1 && pseudoElement == "" { // no need wrap the selectors in compoundSelector
 		return selectors[0], nil
 	}
-	return compoundSelector{selectors: selectors}, nil
+	return compoundSelector{selectors: selectors, pseudoElement: pseudoElement}, nil
 }
 
 // parseSelector parses a selector that may include combinators.
diff --git a/selector.go b/selector.go
index 18ce116..d7631e0 100644
--- a/selector.go
+++ b/selector.go
@@ -16,14 +16,16 @@ type Matcher interface {
 }
 
 // Sel is the interface for all the functionality provided by selectors.
-// It is currently the same as Matcher, but other methods may be added in the
-// future.
 type Sel interface {
 	Matcher
 	Specificity() Specificity
+
+	// Return a pseudo-element, or an empty string.
+	PseudoElement() string
 }
 
-// Parse parses a selector.
+// Parse parses a selector. Use `ParseWithPseudoElement`
+// if you need support for pseudo-elements.
 func Parse(sel string) (Sel, error) {
 	p := &parser{s: sel}
 	compiled, err := p.parseSelector()
@@ -38,7 +40,25 @@ func Parse(sel string) (Sel, error) {
 	return compiled, nil
 }
 
+// ParseWithPseudoElement parses a single selector,
+// with support for pseudo-element.
+func ParseWithPseudoElement(sel string) (Sel, error) {
+	p := &parser{s: sel, acceptPseudoElements: true}
+	compiled, err := p.parseSelector()
+	if err != nil {
+		return nil, err
+	}
+
+	if p.i < len(sel) {
+		return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
+	}
+
+	return compiled, nil
+}
+
 // ParseGroup parses a selector, or a group of selectors separated by commas.
+// Use `ParseGroupWithPseudoElements`
+// if you need support for pseudo-elements.
 func ParseGroup(sel string) (SelectorGroup, error) {
 	p := &parser{s: sel}
 	compiled, err := p.parseSelectorGroup()
@@ -53,6 +73,22 @@ func ParseGroup(sel string) (SelectorGroup, error) {
 	return compiled, nil
 }
 
+// ParseGroupWithPseudoElements parses a selector, or a group of selectors separated by commas.
+// It supports pseudo-elements.
+func ParseGroupWithPseudoElements(sel string) (SelectorGroup, error) {
+	p := &parser{s: sel, acceptPseudoElements: true}
+	compiled, err := p.parseSelectorGroup()
+	if err != nil {
+		return nil, err
+	}
+
+	if p.i < len(sel) {
+		return nil, fmt.Errorf("parsing %q: %d bytes left over", sel, len(sel)-p.i)
+	}
+
+	return compiled, nil
+}
+
 // A Selector is a function which tells whether a node matches or not.
 //
 // This type is maintained for compatibility; I recommend using the newer and
@@ -182,6 +218,10 @@ func (c tagSelector) Specificity() Specificity {
 	return Specificity{0, 0, 1}
 }
 
+func (c tagSelector) PseudoElement() string {
+	return ""
+}
+
 type classSelector struct {
 	class string
 }
@@ -197,6 +237,10 @@ func (c classSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c classSelector) PseudoElement() string {
+	return ""
+}
+
 type idSelector struct {
 	id string
 }
@@ -212,6 +256,10 @@ func (c idSelector) Specificity() Specificity {
 	return Specificity{1, 0, 0}
 }
 
+func (c idSelector) PseudoElement() string {
+	return ""
+}
+
 type attrSelector struct {
 	key, val, operation string
 	regexp              *regexp.Regexp
@@ -352,6 +400,10 @@ func (c attrSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c attrSelector) PseudoElement() string {
+	return ""
+}
+
 // ---------------- Pseudo class selectors ----------------
 // we use severals concrete types of pseudo-class selectors
 
@@ -415,6 +467,10 @@ func (s relativePseudoClassSelector) Specificity() Specificity {
 	return max
 }
 
+func (c relativePseudoClassSelector) PseudoElement() string {
+	return ""
+}
+
 type containsPseudoClassSelector struct {
 	own   bool
 	value string
@@ -436,6 +492,10 @@ func (s containsPseudoClassSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c containsPseudoClassSelector) PseudoElement() string {
+	return ""
+}
+
 type regexpPseudoClassSelector struct {
 	own    bool
 	regexp *regexp.Regexp
@@ -488,6 +548,10 @@ func (s regexpPseudoClassSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c regexpPseudoClassSelector) PseudoElement() string {
+	return ""
+}
+
 type nthPseudoClassSelector struct {
 	a, b         int
 	last, ofType bool
@@ -623,6 +687,10 @@ func (s nthPseudoClassSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c nthPseudoClassSelector) PseudoElement() string {
+	return ""
+}
+
 type onlyChildPseudoClassSelector struct {
 	ofType bool
 }
@@ -661,6 +729,10 @@ func (s onlyChildPseudoClassSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c onlyChildPseudoClassSelector) PseudoElement() string {
+	return ""
+}
+
 type inputPseudoClassSelector struct{}
 
 // Matches input, select, textarea and button elements.
@@ -672,6 +744,10 @@ func (s inputPseudoClassSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c inputPseudoClassSelector) PseudoElement() string {
+	return ""
+}
+
 type emptyElementPseudoClassSelector struct{}
 
 // Matches empty elements.
@@ -694,6 +770,10 @@ func (s emptyElementPseudoClassSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c emptyElementPseudoClassSelector) PseudoElement() string {
+	return ""
+}
+
 type rootPseudoClassSelector struct{}
 
 // Match implements :root
@@ -711,8 +791,13 @@ func (s rootPseudoClassSelector) Specificity() Specificity {
 	return Specificity{0, 1, 0}
 }
 
+func (c rootPseudoClassSelector) PseudoElement() string {
+	return ""
+}
+
 type compoundSelector struct {
-	selectors []Sel
+	selectors     []Sel
+	pseudoElement string
 }
 
 // Matches elements if each sub-selectors matches.
@@ -734,9 +819,17 @@ func (s compoundSelector) Specificity() Specificity {
 	for _, sel := range s.selectors {
 		out = out.Add(sel.Specificity())
 	}
+	if s.pseudoElement != "" {
+		// https://drafts.csswg.org/selectors-3/#specificity
+		out = out.Add(Specificity{0, 0, 1})
+	}
 	return out
 }
 
+func (c compoundSelector) PseudoElement() string {
+	return c.pseudoElement
+}
+
 type combinedSelector struct {
 	first      Sel
 	combinator byte
@@ -818,6 +911,15 @@ func (s combinedSelector) Specificity() Specificity {
 	return spec
 }
 
+// on combinedSelector, a pseudo-element only makes sens on the last
+// selector, although others increase specificity.
+func (c combinedSelector) PseudoElement() string {
+	if c.second == nil {
+		return ""
+	}
+	return c.second.PseudoElement()
+}
+
 // A SelectorGroup is a list of selectors, which matches if any of the
 // individual selectors matches.
 type SelectorGroup []Sel
diff --git a/selector_test.go b/selector_test.go
index 82598c4..4a6c974 100644
--- a/selector_test.go
+++ b/selector_test.go
@@ -614,6 +614,14 @@ var selectorTests = []selectorTest{
 			`<a href="http://www.foo.com"></a>`,
 		},
 	},
+	{
+		`<html><head></head><body><p></p><div></div><span></span><a></a><form></form></body></html>`,
+		"body > *:nth-child(3n+2)",
+		[]string{
+			"<div></div>",
+			"<form></form>",
+		},
+	},
 }
 
 func setup(selector, testHTML string) (Selector, *html.Node, error) {
@@ -634,6 +642,7 @@ func TestSelectors(t *testing.T) {
 		s, doc, err := setup(test.selector, test.HTML)
 		if err != nil {
 			t.Error(err)
+			continue
 		}
 
 		matches := s.MatchAll(doc)
@@ -710,3 +719,73 @@ func TestMatchers(t *testing.T) {
 		}
 	}
 }
+
+type testPseudo struct {
+	HTML, selector string
+	spec           Specificity
+	pseudo         string
+}
+
+var testsPseudo = []testPseudo{
+	{
+		HTML:     `<html><body><ul><ol><li id="s12" class="red level"></li></ol></ul></body></html>`,
+		selector: "#s12:not(FOO)::before",
+		spec:     Specificity{1, 0, 2},
+		pseudo:   "before",
+	},
+	{
+		HTML:     `<html><body><ul><ol><li id="s12" class="red level"></li></ol></ul></body></html>`,
+		selector: "#s12::first-line",
+		spec:     Specificity{1, 0, 1},
+		pseudo:   "first-line",
+	},
+	{
+		HTML:     `<html><body><ul><ol><li id="s12" class="red level"></li></ol></ul></body></html>`,
+		selector: "ol > #s12:first-line",
+		spec:     Specificity{1, 0, 2},
+		pseudo:   "first-line",
+	},
+	{
+		HTML:     `<html><body><ul><ol><li id="s12" class="red level"></li></ol></ul></body></html>`,
+		selector: "#s12:not(FOO)::after",
+		spec:     Specificity{1, 0, 2},
+		pseudo:   "after",
+	},
+	{
+		HTML:     `<html><body><ul><ol><li id="s12" class="red level"></li></ol></ul></body></html>`,
+		selector: "LI.red.level:before",
+		spec:     Specificity{0, 2, 2},
+		pseudo:   "before",
+	},
+}
+
+func TestPseudoElement(t *testing.T) {
+	for _, test := range testsPseudo {
+		s, err := ParseWithPseudoElement(test.selector)
+		if err != nil {
+			t.Fatalf("error compiling %q: %s", test.selector, err)
+		}
+
+		if _, err = Parse(test.selector); err == nil {
+			t.Fatalf("selector %s with pseudo-element should not compile", test.selector)
+		}
+
+		doc, err := html.Parse(strings.NewReader(test.HTML))
+		if err != nil {
+			t.Fatalf("error parsing %q: %s", test.HTML, err)
+		}
+
+		body := doc.FirstChild.LastChild
+		testNode := body.FirstChild.FirstChild.LastChild
+		if !s.Match(testNode) {
+			t.Errorf("%s didn't match (html tree : \n %s) \n", test.selector, nodeString(doc))
+			continue
+		}
+		if s.Specificity() != test.spec {
+			t.Errorf("wrong specificity : expected %v got %v", test.spec, s.Specificity())
+		}
+		if s.PseudoElement() != test.pseudo {
+			t.Errorf("wrong pseudo-element : expected %s got %s", test.pseudo, s.PseudoElement())
+		}
+	}
+}
diff --git a/specificity_test.go b/specificity_test.go
index b9d47ed..338e794 100644
--- a/specificity_test.go
+++ b/specificity_test.go
@@ -1,6 +1,7 @@
 package cascadia
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 
@@ -82,16 +83,24 @@ var testsSpecificity = []testSpec{
 	},
 }
 
+func setupSel(selector, HTML string) (Sel, *html.Node, error) {
+	s, err := Parse(selector)
+	if err != nil {
+		return nil, nil, fmt.Errorf("error compiling %q: %s", selector, err)
+	}
+
+	doc, err := html.Parse(strings.NewReader(HTML))
+	if err != nil {
+		return nil, nil, fmt.Errorf("error parsing %q: %s", HTML, err)
+	}
+	return s, doc, nil
+}
+
 func TestSpecificity(t *testing.T) {
 	for _, test := range testsSpecificity {
-		s, err := Parse(test.selector)
-		if err != nil {
-			t.Fatalf("error compiling %q: %s", test.selector, err)
-		}
-
-		doc, err := html.Parse(strings.NewReader(test.HTML))
+		s, doc, err := setupSel(test.selector, test.HTML)
 		if err != nil {
-			t.Fatalf("error parsing %q: %s", test.HTML, err)
+			t.Fatal(err)
 		}
 		body := doc.FirstChild.LastChild
 		testNode := body.FirstChild.FirstChild.LastChild