diff --git a/.bundle/config b/.bundle/config
new file mode 100644
index 00000000..8ebbe30e
--- /dev/null
+++ b/.bundle/config
@@ -0,0 +1,2 @@
+--- 
+BUNDLE_DISABLE_SHARED_GEMS: "1"
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 00000000..0bb98b1d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+*.swp
+tmp
+pkg
+.swo
+*~
+
diff --git a/Gemfile b/Gemfile
new file mode 100644
index 00000000..67ed1c19
--- /dev/null
+++ b/Gemfile
@@ -0,0 +1,5 @@
+source "http://rubygems.org"
+gem "cucumber"
+gem "aruba"
+gem "rake"
+gem "rspec"
diff --git a/Gemfile.lock b/Gemfile.lock
new file mode 100644
index 00000000..c6b70145
--- /dev/null
+++ b/Gemfile.lock
@@ -0,0 +1,38 @@
+GEM
+  remote: http://rubygems.org/
+  specs:
+    aruba (0.2.4)
+      background_process
+      cucumber (~> 0.9.3)
+    background_process (1.2)
+    builder (2.1.2)
+    cucumber (0.9.4)
+      builder (~> 2.1.2)
+      diff-lcs (~> 1.1.2)
+      gherkin (~> 2.2.9)
+      json (~> 1.4.6)
+      term-ansicolor (~> 1.0.5)
+    diff-lcs (1.1.2)
+    gherkin (2.2.9)
+      json (~> 1.4.6)
+      term-ansicolor (~> 1.0.5)
+    json (1.4.6)
+    rake (0.8.7)
+    rspec (2.1.0)
+      rspec-core (~> 2.1.0)
+      rspec-expectations (~> 2.1.0)
+      rspec-mocks (~> 2.1.0)
+    rspec-core (2.1.0)
+    rspec-expectations (2.1.0)
+      diff-lcs (~> 1.1.2)
+    rspec-mocks (2.1.0)
+    term-ansicolor (1.0.5)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  aruba
+  cucumber
+  rake
+  rspec
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 00000000..167fc5f2
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,19 @@
+require 'rubygems'
+require 'bundler/setup'
+require 'rake/gempackagetask'
+require 'cucumber/rake/task'
+
+eval("$specification = #{IO.read('appraisal.gemspec')}")
+Rake::GemPackageTask.new($specification) do |package|
+  package.need_zip = true
+  package.need_tar = true
+end
+
+Cucumber::Rake::Task.new(:cucumber) do |t|
+  t.fork = true
+  t.cucumber_opts = ['--format', (ENV['CUCUMBER_FORMAT'] || 'progress')]
+end
+
+desc "Default: run the cucumber scenarios"
+task :default => :cucumber
+
diff --git a/appraisal.gemspec b/appraisal.gemspec
new file mode 100644
index 00000000..69787ffe
--- /dev/null
+++ b/appraisal.gemspec
@@ -0,0 +1,26 @@
+Gem::Specification.new do |s|
+    s.name        = %q{appraisal}
+    s.version     = '0.1'
+    s.summary     = %q{Find out how much your Ruby gems are worth}
+    s.description = %q{appraisal integrates with bundler and rake to test your library against different versions of dependencies in repeatable scenarios called "appraisals."}
+
+    s.files        = Dir['[A-Z]*', 'lib/**/*.rb', 'features/**/*']
+    s.require_path = 'lib'
+    s.test_files   = Dir['features/**/*']
+
+    s.has_rdoc = false
+
+    s.authors = ["Joe Ferris"]
+    s.email   = %q{jferris@thoughtbot.com}
+    s.homepage = "http://github.com/thoughtbot/appraisal"
+
+    s.add_development_dependency('cucumber')
+    s.add_development_dependency('aruba')
+
+    s.add_runtime_dependency('rake')
+    s.add_runtime_dependency('bundler')
+
+    s.platform = Gem::Platform::RUBY
+    s.rubygems_version = %q{1.2.0}
+end
+
diff --git a/features/appraisals.feature b/features/appraisals.feature
new file mode 100644
index 00000000..3addbc93
--- /dev/null
+++ b/features/appraisals.feature
@@ -0,0 +1,57 @@
+Feature: run a rake task through several appraisals
+
+  Background:
+    Given a directory named "projecto"
+    When I cd to "projecto"
+    And I write to "Gemfile" with:
+    """
+    source "http://rubygems.org"
+    gem "rake"
+    gem "factory_girl"
+    """
+    When I add "appraisal" from this project as a dependency
+    And I write to "Appraisals" with:
+    """
+    appraise "1.3.2" do
+      gem "factory_girl", "1.3.2"
+    end
+    appraise "1.3.0" do
+      gem "factory_girl", "1.3.0"
+    end
+    """
+    When I write to "Rakefile" with:
+    """
+    require 'rubygems'
+    require 'bundler/setup'
+    require 'appraisal'
+    task :version do
+      require 'factory_girl'
+      puts "Loaded #{Factory::VERSION}"
+    end
+    task :default => :version
+    """
+    When I successfully run "rake appraisal:install --trace"
+
+  @disable-bundler
+  Scenario: run a specific task with one appraisal
+    When I successfully run "rake appraisal:1.3.0 version --trace"
+    Then the output should contain "Loaded 1.3.0"
+
+  @disable-bundler
+  Scenario: run a specific task with all appraisals
+    When I successfully run "rake appraisal version --trace"
+    Then the output should contain "Loaded 1.3.0"
+    And the output should contain "Loaded 1.3.2"
+    And the output should not contain "Invoke version"
+
+  @disable-bundler
+  Scenario: run the default task with one appraisal
+    When I successfully run "rake appraisal:1.3.0 --trace"
+    Then the output should contain "Loaded 1.3.0"
+
+  @disable-bundler
+  Scenario: run the default task with all appraisals
+    When I successfully run "rake appraisal --trace"
+    Then the output should contain "Loaded 1.3.0"
+    And the output should contain "Loaded 1.3.2"
+
diff --git a/features/step_definitions/dependency_steps.rb b/features/step_definitions/dependency_steps.rb
new file mode 100644
index 00000000..36864d48
--- /dev/null
+++ b/features/step_definitions/dependency_steps.rb
@@ -0,0 +1,4 @@
+When /^I add "([^"]*)" from this project as a dependency$/ do |gem_name|
+  append_to_file('Gemfile', %{\ngem "#{gem_name}", :path => "#{PROJECT_ROOT}"})
+end
+
diff --git a/features/support/env.rb b/features/support/env.rb
new file mode 100644
index 00000000..2c40011a
--- /dev/null
+++ b/features/support/env.rb
@@ -0,0 +1,4 @@
+require 'aruba'
+
+PROJECT_ROOT = File.expand_path(File.join(File.dirname(__FILE__), '..', '..')).freeze
+
diff --git a/lib/appraisal.rb b/lib/appraisal.rb
new file mode 100644
index 00000000..131292db
--- /dev/null
+++ b/lib/appraisal.rb
@@ -0,0 +1,4 @@
+require 'appraisal/task'
+
+Appraisal::Task.new
+
diff --git a/lib/appraisal/appraisal.rb b/lib/appraisal/appraisal.rb
new file mode 100644
index 00000000..6737f434
--- /dev/null
+++ b/lib/appraisal/appraisal.rb
@@ -0,0 +1,46 @@
+require 'appraisal/gemfile'
+require 'appraisal/command'
+require 'fileutils'
+
+module Appraisal
+  # Represents one appraisal and its dependencies
+  class Appraisal
+    attr_reader :name, :gemfile
+
+    def initialize(name, source_gemfile)
+      @name = name
+      @gemfile = source_gemfile.dup
+    end
+
+    def gem(name, *requirements)
+      gemfile.gem(name, *requirements)
+    end
+
+    def write_gemfile
+      ::File.open(gemfile_path, "w") do |file|
+        file.puts("# This file was generated by Appraisal")
+        file.puts
+        file.write(gemfile.to_s)
+      end
+    end
+
+    def install
+      Command.new("bundle install --gemfile=#{gemfile_path}").run
+    end
+
+    def gemfile_path
+      unless ::File.exist?(gemfile_root)
+        FileUtils.mkdir(gemfile_root)
+      end
+
+      ::File.join(gemfile_root, "#{name}.gemfile")
+    end
+
+    private
+
+    def gemfile_root
+      "gemfiles"
+    end
+  end
+end
+
diff --git a/lib/appraisal/command.rb b/lib/appraisal/command.rb
new file mode 100644
index 00000000..71b2c11c
--- /dev/null
+++ b/lib/appraisal/command.rb
@@ -0,0 +1,53 @@
+module Appraisal
+  # Executes commands with a clean environment
+  class Command
+    BUNDLER_ENV_VARS = %w(RUBYOPT BUNDLE_PATH BUNDLE_BIN_PATH BUNDLE_GEMFILE).freeze
+
+    def self.from_args(gemfile)
+      command = ([$0] + ARGV.slice(1, ARGV.size)).join(' ')
+      new(command, gemfile)
+    end
+
+    def initialize(command, gemfile = nil)
+      @original_env = {}
+      @gemfile = gemfile
+      @command = command
+    end
+
+    def run
+      announce
+      with_clean_env { Kernel.system(@command) }
+    end
+
+    def exec
+      announce
+      with_clean_env { Kernel.exec(@command) }
+    end
+
+    private
+
+    def with_clean_env
+      unset_bundler_env_vars
+      ENV['BUNDLE_GEMFILE'] = @gemfile
+      yield
+    ensure
+      restore_env
+    end
+
+    def announce
+      puts ">> BUNDLE_GEMFILE=#{@gemfile} #{@command}"
+    end
+
+    def unset_bundler_env_vars
+      BUNDLER_ENV_VARS.each do |key|
+        @original_env[key] = ENV[key]
+        ENV[key] = nil
+      end
+    end
+
+    def restore_env
+      @original_env.each { |key, value| ENV[key] = value }
+    end
+  end
+end
+
diff --git a/lib/appraisal/dependency.rb b/lib/appraisal/dependency.rb
new file mode 100644
index 00000000..c44c6cd0
--- /dev/null
+++ b/lib/appraisal/dependency.rb
@@ -0,0 +1,27 @@
+module Appraisal
+  # Dependency on a gem and optional version requirements
+  class Dependency
+    attr_reader :name, :requirements
+
+    def initialize(name, requirements)
+      @name = name
+      @requirements = requirements
+    end
+
+    def to_s
+      gem_name = %{gem "#{name}"}
+      if requirements.nil? || requirements.empty?
+        gem_name
+      else
+        "#{gem_name}, #{inspect_requirements}"
+      end
+    end
+
+    private
+
+    def inspect_requirements
+      requirements.map { |requirement| requirement.inspect }.join(", ")
+    end
+  end
+end
+
diff --git a/lib/appraisal/file.rb b/lib/appraisal/file.rb
new file mode 100644
index 00000000..06926508
--- /dev/null
+++ b/lib/appraisal/file.rb
@@ -0,0 +1,41 @@
+require 'appraisal/appraisal'
+require 'appraisal/gemfile'
+
+module Appraisal
+  # Loads and parses Appraisal files
+  class File
+    attr_reader :appraisals, :gemfile
+
+    def self.each(&block)
+      new.each(&block)
+    end
+
+    def initialize
+      @appraisals = []
+      @gemfile = Gemfile.new
+      @gemfile.load('Gemfile')
+      run(IO.read(path))
+    end
+
+    def each(&block)
+      appraisals.each(&block)
+    end
+
+    def appraise(name, &block)
+      @appraisals << Appraisal.new(name, gemfile).tap do |appraisal|
+        appraisal.instance_eval(&block)
+      end
+    end
+
+    private
+
+    def run(definitions)
+      instance_eval definitions, __FILE__, __LINE__
+    end
+
+    def path
+      'Appraisals'
+    end
+  end
+end
+
diff --git a/lib/appraisal/gemfile.rb b/lib/appraisal/gemfile.rb
new file mode 100644
index 00000000..3916d22e
--- /dev/null
+++ b/lib/appraisal/gemfile.rb
@@ -0,0 +1,42 @@
+require 'appraisal/dependency'
+
+module Appraisal
+  # Load bundler Gemfiles and merge dependencies
+  class Gemfile
+    attr_reader :dependencies
+
+    def initialize
+      @dependencies = {}
+    end
+
+    def load(path)
+      run(IO.read(path))
+    end
+
+    def run(definitions)
+      instance_eval(definitions, __FILE__, __LINE__)
+    end
+
+    def gem(name, *requirements)
+      @dependencies[name] = Dependency.new(name, requirements)
+    end
+
+    def source(source)
+      @source = source
+    end
+
+    def to_s
+      %{source "#{@source}"\n} <<
+        dependencies.values.map { |dependency| dependency.to_s }.join("\n")
+    end
+
+    def dup
+      Gemfile.new.tap do |gemfile|
+        gemfile.source @source
+        dependencies.values.each do |dependency|
+          gemfile.gem(dependency.name, *dependency.requirements)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/appraisal/task.rb b/lib/appraisal/task.rb
new file mode 100644
index 00000000..11ce02ae
--- /dev/null
+++ b/lib/appraisal/task.rb
@@ -0,0 +1,44 @@
+require 'appraisal/file'
+require 'rake/tasklib'
+
+module Appraisal
+  # Defines tasks for installing appraisal dependencies and running other tasks
+  # for a given appraisal.
+  class Task < Rake::TaskLib
+    def initialize
+      namespace :appraisal do
+        desc "Generate a Gemfile for each appraisal"
+        task :gemfiles do
+          File.each do |appraisal|
+            appraisal.write_gemfile
+          end
+        end
+
+        desc "Resolve and install dependencies for each appraisal"
+        task :install => :gemfiles do
+          File.each do |appraisal|
+            appraisal.install
+          end
+        end
+
+        File.each do |appraisal|
+          desc "Run the given task for appraisal #{appraisal.name}"
+          task appraisal.name do
+            Command.from_args(appraisal.gemfile_path).exec
+          end
+        end
+
+        task :all do
+          File.each do |appraisal|
+            Command.from_args(appraisal.gemfile_path).run
+          end
+          exit
+        end
+      end
+
+      desc "Run the given task for all appraisals"
+      task :appraisal => "appraisal:all"
+    end
+  end
+end
+