diff --git a/features/preview_changes.feature b/features/preview_changes.feature
new file mode 100644
index 00000000..f3a3bda1
--- /dev/null
+++ b/features/preview_changes.feature
@@ -0,0 +1,18 @@
+Feature: Preview Changes
+  In order to run quickly, we should update internal caches on file changes
+  
+  Scenario: A template changes contents during preview
+    Given the Server is running at "preview-app"
+    And the file "source/content.html.erb" has the contents
+      """
+      Hello World
+      """
+    When I go to "/content.html"
+    Then I should see "Hello World"
+    And the file "source/content.html.erb" has the contents
+      """
+      Hola Mundo
+      """
+    When I go to "/content.html"
+    Then I should see "Hola Mundo"
+    
\ No newline at end of file
diff --git a/fixtures/preview-app/config.rb b/fixtures/preview-app/config.rb
new file mode 100644
index 00000000..e69de29b
diff --git a/fixtures/preview-app/source/content.html.erb b/fixtures/preview-app/source/content.html.erb
new file mode 100644
index 00000000..ade1f58b
--- /dev/null
+++ b/fixtures/preview-app/source/content.html.erb
@@ -0,0 +1 @@
+Hola Mundo
\ No newline at end of file
diff --git a/fixtures/preview-app/source/layout.erb b/fixtures/preview-app/source/layout.erb
new file mode 100644
index 00000000..cd9bb66d
--- /dev/null
+++ b/fixtures/preview-app/source/layout.erb
@@ -0,0 +1 @@
+<%= yield %>
\ No newline at end of file
diff --git a/lib/middleman/step_definitions/middleman_steps.rb b/lib/middleman/step_definitions/middleman_steps.rb
index 02139beb..b0c9ed77 100644
--- a/lib/middleman/step_definitions/middleman_steps.rb
+++ b/lib/middleman/step_definitions/middleman_steps.rb
@@ -1,3 +1,13 @@
 Given /^a project at "([^\"]*)"$/ do |dirname|
   @target = File.join(PROJECT_ROOT_PATH, "fixtures", dirname)
+end
+
+Then /^the file "([^\"]*)" has the contents$/ do |path, contents|
+  file_path = File.expand_path(path, @target)
+  File.open(file_path, 'w') { |f| f.write(contents) }
+  step %Q{the file "#{path}" did change}
+end
+
+Then /^the file "([^\"]*)" did change$/ do |path|
+  @server_inst.file_did_change(path)
 end
\ No newline at end of file
diff --git a/lib/middleman/step_definitions/server_steps.rb b/lib/middleman/step_definitions/server_steps.rb
index d0f44041..189b0733 100644
--- a/lib/middleman/step_definitions/server_steps.rb
+++ b/lib/middleman/step_definitions/server_steps.rb
@@ -22,6 +22,8 @@ Given /^current environment is "([^\"]*)"$/ do |env|
 end
 
 Given /^the Server is running at "([^\"]*)"$/ do |app_path|
+  step %Q{a project at "#{app_path}"}
+  
   initialize_commands = @initialize_commands || []
   initialize_commands.unshift lambda { 
     set :root, File.join(PROJECT_ROOT_PATH, "fixtures", app_path)