diff --git a/lib/formtastic/form_builder.rb b/lib/formtastic/form_builder.rb
index 1d04a8a5b..583b62d6c 100644
--- a/lib/formtastic/form_builder.rb
+++ b/lib/formtastic/form_builder.rb
@@ -69,6 +69,12 @@ def self.configure(name, value = nil)
     #
     # @todo is there a way to test the params structure of the Rails helper we wrap to ensure forward compatibility?
     def semantic_fields_for(record_or_name_or_array, *args, &block)
+      # Add a :parent_builder to the args so that nested translations can be possible in Rails 3
+      options = args.shift || {}
+      options[:parent_builder] ||= self
+      args.unshift(options)
+      
+      # Wrap the Rails helper
       fields_for(record_or_name_or_array, *args, &block)
     end
     
diff --git a/lib/formtastic/localized_string.rb b/lib/formtastic/localized_string.rb
index 631c04fc0..6bab5bc7f 100644
--- a/lib/formtastic/localized_string.rb
+++ b/lib/formtastic/localized_string.rb
@@ -35,6 +35,7 @@ def localized_string(key, value, type, options = {}) #:nodoc:
 
         if use_i18n
           model_name, nested_model_name  = normalize_model_name(self.model_name.underscore)
+          
           action_name = template.params[:action].to_s rescue ''
           attribute_name = key.to_s
 
@@ -73,9 +74,17 @@ def model_name
     end
 
     def normalize_model_name(name)
-      if name =~ /(.+)\[(.+)\]/
+      if !name =~ /\[/ && self.respond_to?(:builder) && builder.respond_to?(:parent_builder) && builder.parent_builder.object_name
+        # Rails 3.1 nested builder case
+        [builder.parent_builder.object_name.to_s, name]
+      elsif name =~ /(.+)\[(.+)\]/
+        # Rails 3 (and 3.1?) nested builder case with :post rather than @post
         [$1, $2]
+      elsif self.respond_to?(:builder) && builder.respond_to?(:options) && builder.options.key?(:parent_builder)
+        # Rails 3.0 nested builder work-around case, where :parent_builder is provided by f.semantic_form_for
+        [builder.options[:parent_builder].object_name.to_s, name]
       else
+        # Non-nested case
         [name]
       end
     end
diff --git a/spec/i18n_spec.rb b/spec/i18n_spec.rb
index 46f10ac00..31f7d47e9 100644
--- a/spec/i18n_spec.rb
+++ b/spec/i18n_spec.rb
@@ -87,14 +87,14 @@
 
       ::I18n.backend.store_translations :en, {:formtastic => {
           :labels => {
-              :title    => "Hello world!",
+              :author   => { :name => "Top author name transation" },
               :post     => {:title => "Hello post!", :author => {:name => "Hello author name!"}},
               :project  => {:title => "Hello project!"},
-              :line_item => {:name => "Hello line item name!"}
             }
         }, :helpers => {
           :label => {
-            :post => {:author => "Written by"}
+            :post => {:body => "Elaborate..." },
+            :author => { :login => "Hello login" }
           }
         }}
 
@@ -130,10 +130,10 @@
       end
     end
 
-    xit 'should be able to translate nested objects with nested translations' do
+    it 'should be able to translate nested objects with nested translations' do
       with_config :i18n_lookups_by_default, true do
         concat(semantic_form_for(@new_post) do |builder|
-          concat(builder.fields_for(:author) do |f|
+          concat(builder.semantic_fields_for(@new_post.author) do |f|
             concat(f.input(:name))
           end)
         end)
@@ -141,23 +141,45 @@
       end
     end
 
-    xit 'should be able to translate nested objects with top level translations' do
+    it 'should be able to translate nested objects with top level translations' do
       with_config :i18n_lookups_by_default, true do
-        concat(semantic_form_for(:order, :url => 'http://test.host') do |builder|
-          builder.fields_for(:line_item) do |f|
+        concat(semantic_form_for(@new_post) do |builder|
+          builder.semantic_fields_for(@new_post.author) do |f|
             concat(f.input(:name))
           end
         end)
-        output_buffer.should have_tag("form label", /Hello line item name!/)
+        output_buffer.should have_tag("form label", /Hello author name!/)
+      end
+    end
+    
+    it 'should be able to translate nested forms with top level translations' do
+      with_config :i18n_lookups_by_default, true do
+        concat(semantic_form_for(:post) do |builder|
+          builder.semantic_fields_for(:author) do |f|
+            concat(f.input(:name))
+          end
+        end)
+        output_buffer.should have_tag("form label", /Hello author name!/)
       end
     end
 
-    xit 'should be able to translate helper label as Rails does' do
+    it 'should be able to translate helper label as Rails does' do
       with_config :i18n_lookups_by_default, true do
         concat(semantic_form_for(@new_post) do |builder|
-          concat(builder.input(:author))
+          concat(builder.input(:body))
+        end)
+        output_buffer.should have_tag("form label", /Elaborate/)
+      end
+    end
+    
+    it 'should be able to translate nested helper label as Rails does' do
+      with_config :i18n_lookups_by_default, true do
+        concat(semantic_form_for(@new_post) do |builder|
+          concat(builder.inputs :for => @new_post.author do |f|
+            concat(f.input(:login))
+          end)
         end)
-        output_buffer.should have_tag("form label", /Written by/)
+        output_buffer.should have_tag("form label", /Hello login/)
       end
     end