diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 34791c3417c..5b7c9ecf4aa 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -119,6 +119,25 @@ pub enum ElementCreator {
     ScriptCreated,
 }
 
+pub enum AdjacentPosition {
+    BeforeBegin,
+    AfterEnd,
+    AfterBegin,
+    BeforeEnd,
+}
+
+impl AdjacentPosition {
+    pub fn parse(position: &str) -> Fallible<AdjacentPosition> {
+        match_ignore_ascii_case! { &*position,
+            "beforebegin" => Ok(AdjacentPosition::BeforeBegin),
+            "afterbegin"  => Ok(AdjacentPosition::AfterBegin),
+            "beforeend"   => Ok(AdjacentPosition::BeforeEnd),
+            "afterend"    => Ok(AdjacentPosition::AfterEnd),
+            _             => Err(Error::Syntax)
+        }
+    }
+}
+
 //
 // Element methods
 //
@@ -1252,31 +1271,30 @@ impl Element {
     }
 
     // https://dom.spec.whatwg.org/#insert-adjacent
-    pub fn insert_adjacent(&self, where_: DOMString, node: &Node)
+    pub fn insert_adjacent(&self, where_: AdjacentPosition, node: &Node)
                            -> Fallible<Option<Root<Node>>> {
         let self_node = self.upcast::<Node>();
-        match &*where_ {
-            "beforebegin" => {
+        match where_ {
+            AdjacentPosition::BeforeBegin => {
                 if let Some(parent) = self_node.GetParentNode() {
                     Node::pre_insert(node, &parent, Some(self_node)).map(Some)
                 } else {
                     Ok(None)
                 }
             }
-            "afterbegin" => {
+            AdjacentPosition::AfterBegin => {
                 Node::pre_insert(node, &self_node, self_node.GetFirstChild().r()).map(Some)
             }
-            "beforeend" => {
+            AdjacentPosition::BeforeEnd => {
                 Node::pre_insert(node, &self_node, None).map(Some)
             }
-            "afterend" => {
+            AdjacentPosition::AfterEnd => {
                 if let Some(parent) = self_node.GetParentNode() {
                     Node::pre_insert(node, &parent, self_node.GetNextSibling().r()).map(Some)
                 } else {
                     Ok(None)
                 }
             }
-            _ => Err(Error::Syntax)
         }
     }
 
@@ -1995,6 +2013,7 @@ impl ElementMethods for Element {
     // https://dom.spec.whatwg.org/#dom-element-insertadjacentelement
     fn InsertAdjacentElement(&self, where_: DOMString, element: &Element)
                              -> Fallible<Option<Root<Element>>> {
+        let where_ = try!(AdjacentPosition::parse(&*where_));
         let inserted_node = try!(self.insert_adjacent(where_, element.upcast()));
         Ok(inserted_node.map(|node| Root::downcast(node).unwrap()))
     }
@@ -2006,8 +2025,44 @@ impl ElementMethods for Element {
         let text = Text::new(data, &document_from_node(self));
 
         // Step 2.
+        let where_ = try!(AdjacentPosition::parse(&*where_));
         self.insert_adjacent(where_, text.upcast()).map(|_| ())
     }
+
+    // https://w3c.github.io/DOM-Parsing/#dom-element-insertadjacenthtml
+    fn InsertAdjacentHTML(&self, position: DOMString, text: DOMString)
+                          -> ErrorResult {
+        // Step 1.
+        let position = try!(AdjacentPosition::parse(&*position));
+
+        let context = match position {
+            AdjacentPosition::BeforeBegin | AdjacentPosition::AfterEnd => {
+                match self.upcast::<Node>().GetParentNode() {
+                    Some(ref node) if node.is::<Document>() => {
+                        return Err(Error::NoModificationAllowed)
+                    }
+                    None => return Err(Error::NoModificationAllowed),
+                    Some(node) => node,
+                }
+            }
+            AdjacentPosition::AfterBegin | AdjacentPosition::BeforeEnd => {
+                Root::from_ref(self.upcast::<Node>())
+            }
+        };
+
+        // Step 2.
+        let context = match context.downcast::<Element>() {
+            Some(elem) if elem.local_name() != &atom!("html") ||
+                          !elem.html_element_in_html_document() => Root::from_ref(elem),
+            _ => Root::upcast(HTMLBodyElement::new(atom!("body"), None, &*context.owner_doc()))
+        };
+
+        // Step 3.
+        let fragment = try!(context.upcast::<Node>().parse_fragment(text));
+
+        // Step 4.
+        context.insert_adjacent(position, fragment.upcast()).map(|_| ())
+    }
 }
 
 pub fn fragment_affecting_attributes() -> [Atom; 3] {
diff --git a/components/script/dom/webidls/Element.webidl b/components/script/dom/webidls/Element.webidl
index ee27b78d4e4..48aeed7fbbb 100644
--- a/components/script/dom/webidls/Element.webidl
+++ b/components/script/dom/webidls/Element.webidl
@@ -75,6 +75,8 @@ interface Element : Node {
   Element? insertAdjacentElement(DOMString where_, Element element); // historical
   [Throws]
   void insertAdjacentText(DOMString where_, DOMString data);
+  [Throws]
+  void insertAdjacentHTML(DOMString position, DOMString html);
 };
 
 // http://dev.w3.org/csswg/cssom-view/#extensions-to-the-element-interface
diff --git a/components/script/lib.rs b/components/script/lib.rs
index c2aa794719f..50b0c47ac6b 100644
--- a/components/script/lib.rs
+++ b/components/script/lib.rs
@@ -38,6 +38,7 @@ extern crate canvas;
 extern crate canvas_traits;
 extern crate caseless;
 extern crate core;
+#[macro_use]
 extern crate cssparser;
 extern crate devtools_traits;
 extern crate encoding;
diff --git a/tests/wpt/metadata/domparsing/insert-adjacent.html.ini b/tests/wpt/metadata/domparsing/insert-adjacent.html.ini
index af6749ad7d2..10a4345eeb0 100644
--- a/tests/wpt/metadata/domparsing/insert-adjacent.html.ini
+++ b/tests/wpt/metadata/domparsing/insert-adjacent.html.ini
@@ -3,12 +3,6 @@
   [insertAdjacentHTML(beforebegin, <h3>beforebegin</h3> )]
     expected: FAIL
 
-  [insertAdjacentHTML(afterbegin, <h3>afterbegin</h3> )]
-    expected: FAIL
-
-  [insertAdjacentHTML(beforeend, <h3>beforeend</h3> )]
-    expected: FAIL
-
   [insertAdjacentHTML(afterend, <h3>afterend</h3> )]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/domparsing/insert_adjacent_html.html.ini b/tests/wpt/metadata/domparsing/insert_adjacent_html.html.ini
index a1028c07ebe..552aaec582f 100644
--- a/tests/wpt/metadata/domparsing/insert_adjacent_html.html.ini
+++ b/tests/wpt/metadata/domparsing/insert_adjacent_html.html.ini
@@ -3,87 +3,30 @@
   [beforeBegin content without next sibling]
     expected: FAIL
 
-  [Afterbegin content without next sibling]
-    expected: FAIL
-
-  [BeforeEnd content without next sibling]
-    expected: FAIL
-
   [afterend content without next sibling]
     expected: FAIL
 
   [beforeBegin content again, with next sibling]
     expected: FAIL
 
-  [Afterbegin content again, with next sibling]
-    expected: FAIL
-
-  [BeforeEnd content again, with next sibling]
-    expected: FAIL
-
   [afterend content again, with next sibling]
     expected: FAIL
 
-  [Should throw when inserting with invalid position string]
-    expected: FAIL
-
-  [When the parent node is null, insertAdjacentHTML should throw for beforebegin and afterend (text)]
-    expected: FAIL
-
-  [When the parent node is null, insertAdjacentHTML should throw for beforebegin and afterend (comments)]
-    expected: FAIL
-
-  [When the parent node is null, insertAdjacentHTML should throw for beforebegin and afterend (elements)]
-    expected: FAIL
-
-  [When the parent node is a document, insertAdjacentHTML should throw for beforebegin and afterend (text)]
-    expected: FAIL
-
-  [When the parent node is a document, insertAdjacentHTML should throw for beforebegin and afterend (comments)]
-    expected: FAIL
-
-  [When the parent node is a document, insertAdjacentHTML should throw for beforebegin and afterend (elements)]
-    expected: FAIL
-
-  [Inserting after being and before end should order things correctly]
-    expected: FAIL
-
   [beforeBegin child node not in tree but has parent]
     expected: FAIL
 
-  [Afterbegin child node not in tree but has parent]
-    expected: FAIL
-
-  [BeforeEnd child node not in tree but has parent]
-    expected: FAIL
-
   [afterend child node not in tree but has parent]
     expected: FAIL
 
   [beforeBegin content2 without next sibling]
     expected: FAIL
 
-  [Afterbegin content2 without next sibling]
-    expected: FAIL
-
-  [BeforeEnd content2 without next sibling]
-    expected: FAIL
-
   [afterend content2 without next sibling]
     expected: FAIL
 
   [beforeBegin content2 test again, now that there's a next sibling]
     expected: FAIL
 
-  [Afterbegin content2 test again, now that there's a next sibling]
-    expected: FAIL
-
-  [BeforeEnd content2 test again, now that there's a next sibling]
-    expected: FAIL
-
   [afterend content2 test again, now that there's a next sibling]
     expected: FAIL
 
-  [Inserting kids of the <html> element should not do weird things with implied <body>/<head> tags]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/domparsing/insert_adjacent_html.xhtml.ini b/tests/wpt/metadata/domparsing/insert_adjacent_html.xhtml.ini
index 5ceb4830cb7..9312a8de81a 100644
--- a/tests/wpt/metadata/domparsing/insert_adjacent_html.xhtml.ini
+++ b/tests/wpt/metadata/domparsing/insert_adjacent_html.xhtml.ini
@@ -3,84 +3,30 @@
   [beforeBegin content without next sibling]
     expected: FAIL
 
-  [Afterbegin content without next sibling]
-    expected: FAIL
-
-  [BeforeEnd content without next sibling]
-    expected: FAIL
-
   [afterend content without next sibling]
     expected: FAIL
 
   [beforeBegin content again, with next sibling]
     expected: FAIL
 
-  [Afterbegin content again, with next sibling]
-    expected: FAIL
-
-  [BeforeEnd content again, with next sibling]
-    expected: FAIL
-
   [afterend content again, with next sibling]
     expected: FAIL
 
-  [Should throw when inserting with invalid position string]
-    expected: FAIL
-
-  [When the parent node is null, insertAdjacentHTML should throw for beforebegin and afterend (text)]
-    expected: FAIL
-
-  [When the parent node is null, insertAdjacentHTML should throw for beforebegin and afterend (comments)]
-    expected: FAIL
-
-  [When the parent node is null, insertAdjacentHTML should throw for beforebegin and afterend (elements)]
-    expected: FAIL
-
-  [When the parent node is a document, insertAdjacentHTML should throw for beforebegin and afterend (text)]
-    expected: FAIL
-
-  [When the parent node is a document, insertAdjacentHTML should throw for beforebegin and afterend (comments)]
-    expected: FAIL
-
-  [When the parent node is a document, insertAdjacentHTML should throw for beforebegin and afterend (elements)]
-    expected: FAIL
-
-  [Inserting after being and before end should order things correctly]
-    expected: FAIL
-
   [beforeBegin child node not in tree but has parent]
     expected: FAIL
 
-  [Afterbegin child node not in tree but has parent]
-    expected: FAIL
-
-  [BeforeEnd child node not in tree but has parent]
-    expected: FAIL
-
   [afterend child node not in tree but has parent]
     expected: FAIL
 
   [beforeBegin content2 without next sibling]
     expected: FAIL
 
-  [Afterbegin content2 without next sibling]
-    expected: FAIL
-
-  [BeforeEnd content2 without next sibling]
-    expected: FAIL
-
   [afterend content2 without next sibling]
     expected: FAIL
 
   [beforeBegin content2 test again, now that there's a next sibling]
     expected: FAIL
 
-  [Afterbegin content2 test again, now that there's a next sibling]
-    expected: FAIL
-
-  [BeforeEnd content2 test again, now that there's a next sibling]
-    expected: FAIL
-
   [afterend content2 test again, now that there's a next sibling]
     expected: FAIL