diff --git a/src/servo/content.rs b/src/servo/content.rs
index 7655e6e216f..3e9264dfb1c 100644
--- a/src/servo/content.rs
+++ b/src/servo/content.rs
@@ -1,29 +1,59 @@
-export msg;
+export msg, ping;
 export content;
 
-import gfx::geom::*;
-import dom::rcu::*;
-import dom::base::*;
-import layout::base::{rd_tree_ops, wr_tree_ops};
+import dom::rcu::writer_methods;
+import dom=dom::base;
+import layout::layout;
 
 enum msg {
+    parse(str),
     exit
 }
 
-fn content(layout: chan<layout::layout::msg>) -> chan<msg> {
+enum ping {
+    pong
+}
 
-    task::spawn_listener::<msg> {|po|
-        // TODO: Get a DOM from the parser
-        // let s: int = scope();
+// sends a ping to layout and awaits the response.
+fn join_layout(scope: dom::node_scope,
+               to_layout: chan<layout::msg>) {
+    if scope.is_reader_forked() {
+        comm::listen { |ch|
+            to_layout.send(layout::ping(ch));
+            ch.recv();
+        }
+        scope.reader_joined();
+    }
+}
 
-        // TODO: RCU this stuff over to layout
+fn content(to_layout: chan<layout::msg>) -> chan<msg> {
+    task::spawn_listener::<msg> {|from_master|
+        let scope = dom::node_scope();
         loop {
-            if po.peek() {
+            alt from_master.recv() {
+              parse(filename) {
+                #debug["content: Received filename `%s`", filename];
+
+                // Note: we can parse the next document in parallel
+                // with any previous documents.
+                let stream = html::spawn_parser_task(filename);
+                let root = parser::html_builder::build_dom(scope, stream);
+
+                // Now, join the layout so that they will see the latest
+                // changes we have made.
+                join_layout(scope, to_layout);
+
+                // Send new document to layout.
+                to_layout.send(layout::build(root));
+
+                // Indicate that reader was forked so any further
+                // changes will be isolated.
+                scope.reader_forked();
+              }
+              exit {
+                to_layout.send(layout::exit);
                 break;
-            } else {
-                #debug("content: requesting layout");
-                layout.send(layout::layout::build);
-                std::timer::sleep(1000u);
+              }
             }
         }
     }
diff --git a/src/servo/dom/base.rs b/src/servo/dom/base.rs
index 30c3f9eb210..d1c15c9eff2 100644
--- a/src/servo/dom/base.rs
+++ b/src/servo/dom/base.rs
@@ -1,4 +1,4 @@
-import dom::rcu::{scope, writer_methods};
+import dom::rcu::{writer_methods};
 import gfx::geom::{au, size};
 import layout::base::box;
 import util::tree;
@@ -16,30 +16,37 @@ enum node_kind {
 // The rd_aux data is a (weak) pointer to the primary box.  Note that
 // there may be multiple boxes per DOM node.
 type node = rcu::handle<node_data, box>;
+type node_scope = rcu::scope<node_data, box>;
 
-impl methods for scope<node_data, box> {
+fn node_scope() -> node_scope { rcu::scope() }
+
+impl methods for node_scope {
     fn new_node(+k: node_kind) -> node {
         self.handle(node_data({tree: tree::empty(),
                                kind: k}))
     }
 }
 
-impl of tree::rd_tree_ops<node> for scope<node_data, box> {
+impl of tree::rd_tree_ops<node> for node_scope {
     fn each_child(node: node, f: fn(node) -> bool) {
         tree::each_child(self, node, f)
     }
 
+    fn get_parent(node: node) -> option<node> {
+        tree::get_parent(self, node)
+    }
+
     fn with_tree_fields<R>(node: node, f: fn(tree::fields<node>) -> R) -> R {
-        f(self.rd(node) { |f| f.tree })
+        self.rd(node) { |n| f(n.tree) }
     }
 }
 
-impl of tree::wr_tree_ops<node> for scope<node_data, box> {
+impl of tree::wr_tree_ops<node> for node_scope {
     fn add_child(node: node, child: node) {
         tree::add_child(self, node, child)
     }
 
     fn with_tree_fields<R>(node: node, f: fn(tree::fields<node>) -> R) -> R {
-        f(self.wr(node) { |f| f.tree })
+        self.wr(node) { |n| f(n.tree) }
     }
 }
diff --git a/src/servo/dom/rcu.rs b/src/servo/dom/rcu.rs
index 02233b6ed0c..f54fe0c5a6e 100644
--- a/src/servo/dom/rcu.rs
+++ b/src/servo/dom/rcu.rs
@@ -98,6 +98,10 @@ fn scope<T:send,A>() -> scope<T,A> {
 }
 
 impl writer_methods<T:send,A> for scope<T,A> {
+    fn is_reader_forked() -> bool {
+        self.layout_active
+    }
+
     fn reader_forked() {
         assert !self.layout_active;
         assert self.first_dirty.is_null();
@@ -120,6 +124,7 @@ impl writer_methods<T:send,A> for scope<T,A> {
             self.first_dirty = null_handle();
         }
 
+        assert self.first_dirty.is_null();
         self.layout_active = false;
     }
 
@@ -130,12 +135,11 @@ impl writer_methods<T:send,A> for scope<T,A> {
     }
 
     fn wr<U>(h: handle<T,A>, f: fn(T) -> U) -> U unsafe {
-        if self.layout_active {
-            if h.rd_ptr() == h.wr_ptr() {
-                h.set_wr_ptr(self.clone(h.rd_ptr()));
-                h.set_next_dirty(self.first_dirty);
-                self.first_dirty = h;
-            }
+        if self.layout_active && h.rd_ptr() == h.wr_ptr() {
+            #debug["marking handle %? as dirty", h];
+            h.set_wr_ptr(self.clone(h.rd_ptr()));
+            h.set_next_dirty(self.first_dirty);
+            self.first_dirty = h;
         }
         f(*h.wr_ptr())
     }
diff --git a/src/servo/gfx/renderer.rs b/src/servo/gfx/renderer.rs
index 5a7386ce6e3..2a3ef9d991d 100644
--- a/src/servo/gfx/renderer.rs
+++ b/src/servo/gfx/renderer.rs
@@ -1,12 +1,12 @@
 import platform::osmain;
 import geom::*;
 import comm::*;
-import layout::display_list::*;
+import dl = layout::display_list;
 import azure::*;
 import azure::bindgen::*;
 
 enum msg {
-    render(display_list),
+    render(dl::display_list),
     exit(comm::chan<()>)
 }
 
@@ -15,7 +15,7 @@ fn renderer(osmain: chan<osmain::msg>) -> chan<msg> {
         listen {|draw_target_ch|
             #debug("renderer: beginning rendering loop");
             osmain.send(osmain::begin_drawing(draw_target_ch));
-                
+
             loop {
                 alt po.recv() {
                   render(display_list) {
@@ -38,13 +38,13 @@ fn renderer(osmain: chan<osmain::msg>) -> chan<msg> {
 
 fn draw_display_list(
     draw_target: AzDrawTargetRef,
-    display_list: display_list
+    display_list: dl::display_list
 ) {
     clear(draw_target);
 
     for display_list.each {|item|
         let (r, g, b) = alt check item.item_type {
-          solid_color(r, g, b) { (r, g, b) }
+          dl::solid_color(r, g, b) { (r, g, b) }
         };
         let bounds = (*item).bounds;
 
diff --git a/src/servo/layout/base.rs b/src/servo/layout/base.rs
index f1e34053903..6fc12c7c730 100644
--- a/src/servo/layout/base.rs
+++ b/src/servo/layout/base.rs
@@ -55,6 +55,15 @@ fn linked_box(n: node) -> @box {
     ret b;
 }
 
+fn linked_subtree(p: node) -> @box {
+    let p_box = linked_box(p);
+    for ntree.each_child(p) { |c|
+        let c_box = linked_box(c);
+        btree.add_child(p_box, c_box);
+    }
+    ret p_box;
+}
+
 fn reflow_block(root: @box, available_width: au) {
     // Root here is the root of the reflow, not necessarily the doc as
     // a whole.
diff --git a/src/servo/layout/layout.rs b/src/servo/layout/layout.rs
index 755ec5ef506..e4fe2e5ac60 100644
--- a/src/servo/layout/layout.rs
+++ b/src/servo/layout/layout.rs
@@ -8,56 +8,34 @@ them to be rendered
 import task::*;
 import comm::*;
 import gfx::geom;
-import gfx::geom::*;
 import gfx::renderer;
-import dom::base::*;
-import display_list::*;
+import dom::base::node;
 import dom::rcu::scope;
-import base::{btree, rd_tree_ops, wr_tree_ops};
+import base::{btree, rd_tree_ops, wr_tree_ops, linked_subtree};
+import dl = display_list;
 
 enum msg {
-    build,
+    build(node),
+    ping(chan<content::ping>),
     exit
 }
 
-fn layout(renderer: chan<renderer::msg>) -> chan<msg> {
-
-    spawn_listener::<msg> {|po|
-
-        let r = rand::rng();
-
+fn layout(to_renderer: chan<renderer::msg>) -> chan<msg> {
+    spawn_listener::<msg> { |po|
         loop {
-
-            let s = scope();
-            let ndiv = s.new_node(nk_div);
-            let bdiv = base::linked_box(ndiv);
-
-            iter::repeat(100u) {||
-                let node = s.new_node(nk_img(
-                    size(
-                        int_to_au(r.next() as int % 800),
-                        int_to_au(r.next() as int % 200)
-                    )));
-                s.add_child(ndiv, node);
-                let b = base::linked_box(node);
-                btree.add_child(bdiv, b);
-            }
-
-            alt recv(po) {
-              build {
+            alt po.recv() {
+              ping(ch) { ch.send(content::pong); }
+              exit { break; }
+              build(node) {
                 #debug("layout: received layout request");
-                base::reflow_block(bdiv, int_to_au(800));
-                let dlist = build_display_list(bdiv);
-
-                send(renderer, gfx::renderer::render(dlist));
-              }
-              exit {
-                break;
+                let box = linked_subtree(node);
+                base::reflow_block(box, geom::int_to_au(800));
+                let dlist = build_display_list(box);
+                to_renderer.send(renderer::render(dlist));
               }
             }
         }
     }
-
 }
 
 fn build_display_list(box: @base::box) -> display_list::display_list {
@@ -71,10 +49,12 @@ fn build_display_list(box: @base::box) -> display_list::display_list {
     ret list;
 }
 
-fn box_to_display_item(box: @base::box) -> display_item {
+fn box_to_display_item(box: @base::box) -> dl::display_item {
     let r = rand::rng();
-    let item = display_item({
-        item_type: solid_color(r.next() as u8, r.next() as u8, r.next() as u8),
+    let item = dl::display_item({
+        item_type: dl::solid_color(r.next() as u8,
+                                   r.next() as u8,
+                                   r.next() as u8),
         bounds: box.bounds
     });
     #debug("layout: display item: %?", item);
diff --git a/src/servo/parser/html_builder.rs b/src/servo/parser/html_builder.rs
new file mode 100644
index 00000000000..0d4d1f2a4dc
--- /dev/null
+++ b/src/servo/parser/html_builder.rs
@@ -0,0 +1,38 @@
+// Constructs a DOM tree from an incoming token stream.
+
+import dom::rcu::writer_methods;
+import dom::base::{methods, rd_tree_ops, wr_tree_ops};
+import dom = dom::base;
+import parser = parser::html;
+import html::token;
+
+fn build_dom(scope: dom::node_scope,
+             stream: port<token>) -> dom::node {
+    // The current reference node.
+    let mut cur = scope.new_node(dom::nk_div);
+    loop {
+        let token = stream.recv();
+        #debug["token=%?", token];
+        alt token {
+            parser::to_eof { break; }
+            parser::to_start_tag(_) {
+                let new_node = scope.new_node(dom::nk_div);
+                scope.add_child(cur, new_node);
+                cur = new_node;
+            }
+            parser::to_end_tag(_) {
+                // TODO: Assert that the closing tag has the right name.
+                // TODO: Fail more gracefully (i.e. according to the HTML5
+                //       spec) if we close more tags than we open.
+                cur = scope.get_parent(cur).get();
+            }
+            parser::to_text(_) {
+                // TODO
+            }
+            parser::to_doctype {
+                // TODO: Do something here...
+            }
+        }
+    }
+    ret cur;
+}
diff --git a/src/servo/servo.rc b/src/servo/servo.rc
index 1b3e3464472..a2f25852963 100755
--- a/src/servo/servo.rc
+++ b/src/servo/servo.rc
@@ -35,6 +35,7 @@ mod layout {
 
 mod parser {
     mod html;
+    mod html_builder;
 }
 
 mod platform {
diff --git a/src/servo/servo.rs b/src/servo/servo.rs
index 0318854e2e6..740b3b9f41d 100644
--- a/src/servo/servo.rs
+++ b/src/servo/servo.rs
@@ -3,27 +3,7 @@ import parser::html;
 import parser::html::methods;
 import result::extensions;
 
-fn parse(filename: str) {
-    let file_data = io::read_whole_file(filename).get();
-    let reader = io::bytes_reader(file_data);
-    let parser = html::parser(reader);
-    loop {
-        let t = parser.parse();
-        log(error, #fmt("token: %?", t));
-        if t == html::to_eof { break; }
-    }
-}
-
 fn main(args: [str]) {
-    if args.len() >= 2u {
-        let p = html::spawn_parser_task(args[1]);
-        loop {
-            let token = p.recv();
-            io::println(#fmt("token: %?", token));
-            if token == html::to_eof { break; }
-        }
-    }
-
     // The platform event handler thread
     let osmain = platform::osmain::osmain();
 
@@ -36,14 +16,19 @@ fn main(args: [str]) {
     // The content task
     let content = content::content(layout);
 
-    // Wait for keypress
-    listen {|key_ch|
-        osmain.send(platform::osmain::add_key_handler(key_ch));
-
-        key_ch.recv();
+    // Send each file to render then wait for keypress
+    for args.tail().each { |filename|
+        #debug["master: Sending filename `%s`", filename];
+        content.send(content::parse(filename));
+        #debug["master: Waiting for keypress"];
+        listen {|key_ch|
+            osmain.send(platform::osmain::add_key_handler(key_ch));
+            key_ch.recv();
+        }
     }
 
     // Shut everything down
+    #debug["master: Shut down"];
     content.send(content::exit);
     layout.send(layout::layout::exit);
 
diff --git a/src/servo/util/tree.rs b/src/servo/util/tree.rs
index 8805853a105..a82f822470a 100644
--- a/src/servo/util/tree.rs
+++ b/src/servo/util/tree.rs
@@ -1,3 +1,7 @@
+// A generic tree datatype.
+//
+// TODO: Use traits.
+
 type fields<T> = {
     mut parent: option<T>,
     mut first_child: option<T>,
@@ -38,21 +42,21 @@ fn empty<T>() -> fields<T> {
 }
 
 fn add_child<T:copy,O:wr_tree_ops<T>>(
-    ops: O, node: T, child: T) {
+    ops: O, parent: T, child: T) {
 
     ops.with_tree_fields(child) { |child_tf|
         alt child_tf.parent {
           some(_) { fail "Already has a parent"; }
-          none { child_tf.parent = some(node); }
+          none { child_tf.parent = some(parent); }
         }
 
         assert child_tf.prev_sibling == none;
         assert child_tf.next_sibling == none;
 
-        ops.with_tree_fields(node) { |node_tf|
-            alt node_tf.last_child {
+        ops.with_tree_fields(parent) { |parent_tf|
+            alt parent_tf.last_child {
               none {
-                node_tf.first_child = some(child);
+                parent_tf.first_child = some(child);
               }
 
               some(lc) {
@@ -65,11 +69,15 @@ fn add_child<T:copy,O:wr_tree_ops<T>>(
               }
             }
 
-            node_tf.last_child = some(child);
+            parent_tf.last_child = some(child);
         }
     }
 }
 
+fn get_parent<T:copy,O:rd_tree_ops<T>>(ops: O, node: T) -> option<T> {
+    ops.with_tree_fields(node) { |tf| tf.parent }
+}
+
 #[cfg(test)]
 mod test {
     enum dummy = @{
@@ -129,4 +137,4 @@ mod test {
         }
         assert i == 1u;
     }
-}
\ No newline at end of file
+}