diff --git a/lib/webrat.rb b/lib/webrat.rb
index 4401f1a..26c8dde 100644
--- a/lib/webrat.rb
+++ b/lib/webrat.rb
@@ -35,7 +35,7 @@ module ActionController
         current_page.save_and_open
       end
       
-      [:reloads, :fills_in, :clicks_button, :selects, :chooses, :checks, :unchecks, :clicks_link, :clicks_link_within, :clicks_put_link, :clicks_get_link, :clicks_post_link, :clicks_delete_link].each do |method_name|
+      [:reloads, :fills_in, :clicks_button, :selects, :attaches_file, :chooses, :checks, :unchecks, :clicks_link, :clicks_link_within, :clicks_put_link, :clicks_get_link, :clicks_post_link, :clicks_delete_link].each do |method_name|
         define_method(method_name) do |*args|
           current_page.send(method_name, *args)
         end
diff --git a/lib/webrat/field.rb b/lib/webrat/field.rb
index f6b1a1e..e45a192 100644
--- a/lib/webrat/field.rb
+++ b/lib/webrat/field.rb
@@ -97,6 +97,21 @@ module Webrat
       end
     end
     
+    def replace_param_value(params, oval, nval)
+      output = Hash.new
+      params.each do |key, value|
+        case value
+        when Hash
+          value = replace_param_value(value, oval, nval)
+        when Array
+          value = value.map { |o| o == oval ? nval : oval }
+        when oval
+          value = nval
+        end
+        output[key] = value
+      end
+      output
+    end
   end
   
   class ButtonField < Field
@@ -221,6 +236,15 @@ module Webrat
   end
   
   class FileField < Field
+
+    def to_param
+      if @value.nil?
+        super
+      else
+        replace_param_value(super, @value, ActionController::TestUploadedFile.new(@value))
+      end
+    end
+
   end
 
   class TextField < Field
diff --git a/lib/webrat/page.rb b/lib/webrat/page.rb
index 65e5056..17fcd0e 100644
--- a/lib/webrat/page.rb
+++ b/lib/webrat/page.rb
@@ -88,6 +88,17 @@ module Webrat
       option.choose
     end
 
+    # Verifies that an input file field exists on the current page and sets
+    # its value to the given +file+, so that the file will be uploaded
+    # along with the form.
+    #
+    # Example:
+    #   attaches_file "Photo", "/path/to/the/photo.jpg"
+    def attaches_file(id_or_name_or_label, path)
+      field = find_field(id_or_name_or_label, FileField)
+      field.set(path)
+    end
+
     # Saves the currently loaded page out to RAILS_ROOT/tmp/ and opens it in the default
     # web browser if on OS X. Useful for debugging.
     # 
diff --git a/spec/attaches_file_spec.rb b/spec/attaches_file_spec.rb
new file mode 100644
index 0000000..30111c1
--- /dev/null
+++ b/spec/attaches_file_spec.rb
@@ -0,0 +1,62 @@
+require File.expand_path(File.dirname(__FILE__) + "/spec_helper")
+
+describe "attaches_file" do
+  before do
+    @session = ActionController::Integration::Session.new
+    @session.stubs(:assert_response)
+    @session.stubs(:get_via_redirect)
+    @session.stubs(:response).returns(@response=mock)
+
+    @filename = __FILE__
+    @uploaded_file = mock
+    ActionController::TestUploadedFile.stubs(:new).returns(@uploaded_file)
+  end
+
+  it "should fail if no file field found" do
+    @response.stubs(:body).returns(<<-EOS)
+      <form method="post" action="/widgets">
+      </form>
+    EOS
+    lambda { @session.attaches_file("Doc", "/some/path") }.should raise_error
+  end
+
+  it "should submit empty strings for blank file fields" do
+    @response.stubs(:body).returns(<<-EOS)
+      <form method="post" action="/widgets">
+        <input type="file" id="widget_file" name="widget[file]" />
+        <input type="submit" />
+      </form>
+    EOS
+    @session.expects(:post_via_redirect).with("/widgets", { "widget" => { "file" => "" } })
+    @session.clicks_button
+  end
+
+  it "should submit the attached file" do
+    @response.stubs(:body).returns(<<-EOS)
+      <form method="post" action="/widgets">
+        <label for="widget_file">Document</label>
+        <input type="file" id="widget_file" name="widget[file]" />
+        <input type="submit" />
+      </form>
+    EOS
+    @session.expects(:post_via_redirect).with("/widgets", { "widget" => { "file" => @uploaded_file } })
+    @session.attaches_file "Document", @filename
+    @session.clicks_button
+  end
+
+  it "should support collections" do
+    @response.stubs(:body).returns(<<-EOS)
+      <form method="post" action="/widgets">
+        <label for="widget_file1">Document</label>
+        <input type="file" id="widget_file1" name="widget[files][]" />
+        <label for="widget_file2">Spreadsheet</label>
+        <input type="file" id="widget_file2" name="widget[files][]" />
+        <input type="submit" />
+      </form>
+    EOS
+    @session.expects(:post_via_redirect).with("/widgets", { "widget" => { "files" => [@uploaded_file, @uploaded_file] } })
+    @session.attaches_file "Document", @filename
+    @session.attaches_file "Spreadsheet", @filename
+    @session.clicks_button
+  end
+end