diff --git a/lib/compass/actions.rb b/lib/compass/actions.rb
index 10fd7c5f..95b9b06b 100644
--- a/lib/compass/actions.rb
+++ b/lib/compass/actions.rb
@@ -73,6 +73,13 @@ module Compass
       end
     end
 
+    def remove(file_name)
+      if File.exists?(file_name)
+        File.unlink file_name
+        logger.record :remove, basename(file_name)
+      end
+    end
+
     def basename(file)
       relativize(file) {|f| File.basename(file)}
     end
diff --git a/lib/compass/commands/update_project.rb b/lib/compass/commands/update_project.rb
index 821a94ed..e00e7a8f 100644
--- a/lib/compass/commands/update_project.rb
+++ b/lib/compass/commands/update_project.rb
@@ -21,12 +21,12 @@ module Compass
         end
       end
 
-      def new_compiler_instance(options = {})
+      def new_compiler_instance(additional_options = {})
         Compass::Compiler.new(working_path,
           projectize(Compass.configuration.sass_dir),
           projectize(Compass.configuration.css_dir),
           Compass.sass_engine_options.merge(:quiet => options[:quiet],
-                                            :force => options[:force]).merge(options))
+                                            :force => options[:force]).merge(additional_options))
       end
 
     end
diff --git a/lib/compass/commands/watch_project.rb b/lib/compass/commands/watch_project.rb
index 698d9be9..97eb2fe9 100644
--- a/lib/compass/commands/watch_project.rb
+++ b/lib/compass/commands/watch_project.rb
@@ -7,45 +7,44 @@ module Compass
   module Commands
     class WatchProject < UpdateProject
 
-      attr_accessor :last_update_time
+      attr_accessor :last_update_time, :last_sass_files
 
       def perform
-        puts ">>> Compiling all stylesheets."
-        super
-        self.last_update_time = most_recent_update_time
-        puts ">>> Compass is now watching for changes. Press Ctrl-C to Stop."
+        Signal.trap("INT") do
+          puts ""
+          exit 0
+        end
+        puts ">>> Compass is watching for changes. Press Ctrl-C to Stop."
         loop do
           # TODO: Make this efficient by using filesystem monitoring.
+          compiler = new_compiler_instance(:quiet => true)
+          remove_obsolete_css(compiler)
+          recompile(compiler)
+          sleep 1
+        end
+      end
+
+      def remove_obsolete_css(compiler)
+        sass_files = compiler.sass_files
+        deleted_sass_files = (last_sass_files || []) - sass_files
+        deleted_sass_files.each do |deleted_sass_file|
+          css_file = compiler.corresponding_css_file(deleted_sass_file)
+          remove(css_file) if File.exists?(css_file)
+        end
+        self.last_sass_files = sass_files
+      end
+
+      def recompile(compiler)
+        if file = compiler.out_of_date?
           begin
-            sleep 1
-          rescue Interrupt
-            puts ""
-            exit 0
-          end
-          file, t = should_update?
-          if t
-            begin
-              puts ">>> Change detected to: #{file}"
-              super
-            rescue StandardError => e
-              ::Compass::Exec.report_error(e, options)
-            end
-            self.last_update_time = t
+            puts ">>> Change detected to: #{file}"
+            compiler.run
+          rescue StandardError => e
+            ::Compass::Exec.report_error(e, options)
           end
         end
       end
 
-      def most_recent_update_time
-        Dir.glob(separate("#{projectize(Compass.configuration.sass_dir)}/**/*.sass")).map {|sass_file| File.stat(sass_file).mtime}.max
-      end
-
-      def should_update?
-        t = most_recent_update_time
-        if t > last_update_time
-          file = Dir.glob(separate("#{projectize(Compass.configuration.sass_dir)}/**/*.sass")).detect {|sass_file| File.stat(sass_file).mtime >= t}
-          [file, t]
-        end
-      end
     end
   end
 end
\ No newline at end of file
diff --git a/lib/compass/compiler.rb b/lib/compass/compiler.rb
index 9134553e..84fb3945 100644
--- a/lib/compass/compiler.rb
+++ b/lib/compass/compiler.rb
@@ -22,13 +22,25 @@ module Compass
     end
 
     def css_files
-      @css_files ||= sass_files.map{|sass_file| "#{to}/#{stylesheet_name(sass_file)}.css"}
+      @css_files ||= sass_files.map{|sass_file| corresponding_css_file(sass_file)}
+    end
+
+    def corresponding_css_file(sass_file)
+      "#{to}/#{stylesheet_name(sass_file)}.css"
     end
 
     def target_directories
       css_files.map{|css_file| File.dirname(css_file)}.uniq.sort.sort_by{|d| d.length }
     end
 
+    def out_of_date?
+      sass_files.zip(css_files).each do |sass_filename, css_filename|
+        return sass_filename unless File.exists?(css_filename)
+        return sass_filename if File.stat(sass_filename).mtime > File.stat(css_filename).mtime
+      end
+      false
+    end
+
     def run
       Compass.configure_sass_plugin!
       target_directories.each do |dir|