diff --git a/lib/sinatra/url_for.rb b/lib/sinatra/url_for.rb
index 3dfa1dd..b32631b 100644
--- a/lib/sinatra/url_for.rb
+++ b/lib/sinatra/url_for.rb
@@ -10,10 +10,32 @@ module UrlForHelper
     #   url_for "/"            # Returns "/myapp/"
     #   url_for "/foo"         # Returns "/myapp/foo"
     #   url_for "/foo", :full  # Returns "http://example.com/myapp/foo"
+    #
+    # You can also pass in a hash of options, which will be appended to the
+    # URL as escaped parameters, like so:
+    #
+    #   url_for "/", :x => "y" # Returns "/myapp/?x=y"
+    #   url_for "/foo", :x => "M&Ms" # Returns "/myapp/foo?x=M%26Ms"
+    #
+    # You can also specify the mode:
+    #
+    #   url_for "/foo", :full, :x => "y" # Returns "http://example.com/myapp/foo?x=y"
+    #
     #--
     # See README.rdoc for a list of some of the people who helped me clean
     # up earlier versions of this code.
-    def url_for url_fragment, mode=:path_only
+    def url_for url_fragment, mode=nil, options = nil
+      if mode.nil?
+        mode = :path_only
+      end
+      
+      mode = mode.to_sym unless mode.is_a? Symbol
+      optstring = nil
+      
+      if options.is_a? Hash
+        optstring = '?' + options.map { |k,v| "#{k}=#{URI.escape(v, /[^#{URI::PATTERN::UNRESERVED}]/)}" }.join('&')
+      end
+
       case mode
       when :path_only
         base = request.script_name
@@ -27,9 +49,9 @@ def url_for url_fragment, mode=:path_only
         end
         base = "#{scheme}://#{request.host}#{port}#{request.script_name}"
       else
-        raise TypeError, "Unknown url_for mode #{mode}"
+        raise TypeError, "Unknown url_for mode #{mode.inspect}"
       end
-      "#{base}#{url_fragment}"
+      "#{base}#{url_fragment}#{optstring}"
     end
   end
 
diff --git a/spec/url_for_spec.rb b/spec/url_for_spec.rb
index d34788a..5f1e8e2 100644
--- a/spec/url_for_spec.rb
+++ b/spec/url_for_spec.rb
@@ -3,13 +3,14 @@
 require 'sinatra/url_for'
 require 'rack/test'
 
+# HTML exception pages in tests isn't useful; raise them to rspec so it can
+# tell us about them
+disable :show_exceptions
+enable :raise_errors
+
 get "/" do
   content_type "text/plain"
-  <<"EOD"
-#{url_for("/")}
-#{url_for("/foo")}
-#{url_for("/foo", :full)}
-EOD
+  url_for params[:url], params[:mode], params[:options]
 end
 
 describe Sinatra::UrlForHelper do
@@ -19,13 +20,52 @@ def app
     Sinatra::Application
   end
   
-  it "should return absolute paths and full URLs" do
-    get "/"
+  it "should handle the root URL" do
+    get "/", :url => "/"
+
+    last_response.should be_ok
+    last_response.body.should == "/"
+  end
+  
+  it "should handle sub-URLs" do
+    get "/", :url => "/foo"
+
+    last_response.should be_ok
+    last_response.body.should == "/foo"
+  end
+  
+  it "should provide full paths if asked" do
+    get "/", :url => "/foo", :mode => :full
+
+    last_response.should be_ok
+    last_response.body.should == "http://example.org/foo"
+  end
+  
+  it "should accept options" do
+    get "/", :url => "/foo", :options => { :x => "y" }
+    
+    last_response.should be_ok
+    last_response.body.should == "/foo?x=y"
+  end
+  
+  it "should accept multiple options" do
+    get "/", :url => "/foo", :options => { :x => "y", :bar => "wombat" }
+    
+    last_response.should be_ok
+    last_response.body.should == "/foo?x=y&bar=wombat"
+  end
+  
+  it "should escape option values" do
+    get "/", :url => "/foo", :options => { :x => "M&Ms", :amount => "15%", :equals => "=" }
+    
+    last_response.should be_ok
+    last_response.body.should == "/foo?x=M%26Ms&amount=15%25&equals=%3D"
+  end
+
+  it "should even escape URLs" do
+    get "/", :url => "/foo", :options => { :return_to => "http://example.com/bar?x=y" }
+    
     last_response.should be_ok
-    last_response.body.should == <<EOD
-/
-/foo
-http://example.org/foo
-EOD
+    last_response.body.should == "/foo?return_to=http%3A%2F%2Fexample.com%2Fbar%3Fx%3Dy"
   end
 end