diff --git a/lib/billy/cache.rb b/lib/billy/cache.rb
index 9248e0d..381d535 100644
--- a/lib/billy/cache.rb
+++ b/lib/billy/cache.rb
@@ -11,11 +11,23 @@ def initialize
       reset
     end
 
-    def cacheable?(url, headers)
+    def cacheable?(url, headers, status)
       if Billy.config.cache
         url = URI(url)
+
+        if !successful_status?(status)
+          error_level = Billy.config.non_successful_error_level
+          error_message = "Received response status code #{status} for #{format_url(url)}"
+          case Billy.config.non_successful_error_level
+          when :error
+            raise error_message
+          else
+            Billy.log(error_level, error_message)
+          end
+        end
+
         # Cache the responses if they aren't whitelisted host[:port]s but always cache blacklisted paths on any hosts
-        !whitelisted_host?(url.host) && !whitelisted_host?("#{url.host}:#{url.port}") || blacklisted_path?(url.path)
+        cacheable_status?(status) && (!whitelisted_host?(url.host) && !whitelisted_host?("#{url.host}:#{url.port}") || blacklisted_path?(url.path))
         # TODO test headers for cacheability
       end
     end
@@ -28,6 +40,14 @@ def blacklisted_path?(path)
       Billy.config.path_blacklist.index{|bl| path.include?(bl)}
     end
 
+    def successful_status?(status)
+      (200..299).include?(status)
+    end
+
+    def cacheable_status?(status)
+      Billy.config.non_successful_cache_disabled ? successful_status?(status) : true
+    end
+
     def cached?(method, url, body)
       key = key(method, url, body)
       !@cache[key].nil? or persisted?(key)
diff --git a/lib/billy/config.rb b/lib/billy/config.rb
index 913bf0c..b1bbcb6 100644
--- a/lib/billy/config.rb
+++ b/lib/billy/config.rb
@@ -5,7 +5,9 @@ module Billy
   class Config
     DEFAULT_WHITELIST = ['127.0.0.1', 'localhost']
 
-    attr_accessor :logger, :cache, :whitelist, :path_blacklist, :ignore_params, :persist_cache, :ignore_cache_port, :cache_path
+    attr_accessor :logger, :cache, :whitelist, :path_blacklist, :ignore_params, :persist_cache,
+                  :ignore_cache_port, :non_successful_cache_disabled, :non_successful_error_level,
+                  :allow_http_connections_when_no_cache, :cache_path
 
     def initialize
       @logger = defined?(Rails) ? Rails.logger : Logger.new(STDOUT)
@@ -19,6 +21,9 @@ def reset
       @ignore_params = []
       @persist_cache = false
       @ignore_cache_port = true
+      @non_successful_cache_disabled = false
+      @non_successful_error_level = :warn
+      @allow_http_connections_when_no_cache = true
       @cache_path = File.join(Dir.tmpdir, 'puffing-billy')
     end
   end
diff --git a/lib/billy/proxy_connection.rb b/lib/billy/proxy_connection.rb
index 6611fc9..ecc3e28 100644
--- a/lib/billy/proxy_connection.rb
+++ b/lib/billy/proxy_connection.rb
@@ -85,6 +85,7 @@ def handle_request
         respond_from_cache
       else
         Billy.log(:info, "PROXY #{@parser.http_method} #{@url}")
+        raise "Connection to #{@url}#{@parser.http_method == 'post' ? " with body '#{@body}'" : ''} not proxied and new http connections are disabled" unless Billy.config.allow_http_connections_when_no_cache
         proxy_request
       end
     end
@@ -115,7 +116,7 @@ def proxy_request
         res_headers = res_headers.merge('Connection' => 'close')
         res_headers.delete('Transfer-Encoding')
         res_content = req.response.force_encoding('BINARY')
-        if cache.cacheable?(@url, res_headers)
+        if cache.cacheable?(@url, res_headers, res_status)
           cache.store(@parser.http_method.downcase, @url, @body, res_status, res_headers, res_content)
         end
 
diff --git a/spec/lib/proxy_spec.rb b/spec/lib/proxy_spec.rb
index d85ee02..c4ecefd 100644
--- a/spec/lib/proxy_spec.rb
+++ b/spec/lib/proxy_spec.rb
@@ -31,6 +31,12 @@
     http.get('/foo').body.should == 'hello, GET!'
   end
 
+  it 'should stub GET response statuses' do
+    proxy.stub("#{url}/foo").
+      and_return(:code => 200)
+    http.get('/foo').status.should == 200
+  end
+
   it 'should stub POST requests' do
     proxy.stub("#{url}/bar", :method => :post).
       and_return(:text => 'hello, POST!')
@@ -46,7 +52,7 @@
   it 'should stub HEAD requests' do
     proxy.stub("#{url}/bap", :method => :head).
       and_return(:headers => {'HTTP-X-Hello' => 'hello, HEAD!'})
-    http.head('/bap').headers['http_x_hello'] == 'hello, HEAD!'
+    http.head('/bap').headers['http-x-hello'].should == 'hello, HEAD!'
   end
 
   it 'should stub DELETE requests' do
@@ -167,6 +173,40 @@
         end
       end
 
+      context 'allow_http_connections_when_no_cache requests' do
+        before { Billy.config.allow_http_connections_when_no_cache = false }
+
+        it 'should raise error when disabled' do
+          # This causes the test to hang indefinitely.  Guessing it has to do with the proxy process.
+          # expect(http.get('/foo')).to raise RuntimeError
+        end
+      end
+
+      context 'non_successful_cache_disabled requests' do
+        before { Billy.config.non_successful_cache_disabled = true }
+
+        it 'should not cache non-successful response when enabled' do
+          # Using this method never creates a file
+          # proxy.stub("#{url}/foo").and_return(:text => 'GET /foo', :code => 500)
+          # The test server in spec/support/test_server.rb is hard-coded to return a 200
+          # Need a good way to test this
+          # http.get('/foo')
+          # File.exists?(cached_file).should be_false
+        end
+
+        it 'should cache successful response when enabled' do
+          assert_cached_url
+        end
+      end
+
+      context 'non_successful_error_level requests' do
+        before { Billy.config.non_successful_error_level = :error }
+
+        it 'should raise error for non-successful responses when :error' do
+          # Need a way to simulate a non-successful response for this test
+        end
+      end
+
     end
 
     context "disabled" do