diff --git a/.document b/.document
index 9a5067b..97317c2 100644
--- a/.document
+++ b/.document
@@ -25,4 +25,6 @@ README.EXT
 README.EXT.ja
 README.ja
 
+vagrant.md
+
 doc
diff --git a/.gitignore b/.gitignore
index a9104e9..671616b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,6 +22,7 @@
 .pc
 .ppack
 .svn
+.vagrant
 Makefile
 Makefile.old
 extconf.h
diff --git a/Vagrantfile b/Vagrantfile
new file mode 100644
index 0000000..6548faa
--- /dev/null
+++ b/Vagrantfile
@@ -0,0 +1,110 @@
+# -*- mode: ruby -*-
+# vi: set ft=ruby :
+
+# Vagrant configuration for an MRI Ruby contributor environment.
+Vagrant.configure(2) do |config|
+  config.vm.box = "ubuntu/trusty64"
+
+  # Create a private network, which allows host-only access to the machine
+  # using a specific IP.
+  config.vm.network "private_network", ip: "192.168.33.10"
+
+  # Maps the /vagrant VM folder to the Ruby source folder.  NFS is used for
+  # better performance and may require configuration on the host machine.
+  config.vm.synced_folder '.', '/vagrant', nfs: true
+
+  # Configure the virtual machine with enough access to processors and memory
+  # that it will not be sluggish.
+  config.vm.provider "virtualbox" do |v|
+    host = RbConfig::CONFIG['host_os']
+
+    # Give VM 1/4 system memory & access to all cpu cores on the host
+    case host
+    when /darwin/
+      cpus = `sysctl -n hw.ncpu`.to_i
+      # sysctl returns Bytes and we need to convert to MB
+      mem = `sysctl -n hw.memsize`.to_i / 1024 / 1024 / 4
+    when /linux/
+      cpus = `nproc`.to_i
+      # meminfo shows KB and we need to convert to MB
+      mem = `grep 'MemTotal' /proc/meminfo | sed -e 's/MemTotal://' -e 's/ kB//'`.to_i / 1024 / 4
+    else # sorry Windows folks, I can't help you
+      cpus = 2
+      mem = 1024
+    end
+
+    v.customize ["modifyvm", :id, "--memory", mem]
+    v.customize ["modifyvm", :id, "--cpus", cpus]
+
+    # Fix problem with time on VM getting out of sync with host.
+    v.customize [ "guestproperty", "set", :id, "/VirtualBox/GuestAdd/VBoxService/--timesync-set-threshold", 10000 ]
+  end
+
+  # Provision the Ruby development environment with a shell script.
+  config.vm.provision "shell", inline: <<-SHELL
+    # Install dependencies
+    apt-get update
+    apt-get install -y git
+    apt-get install -y autoconf
+    apt-get install -y make
+    apt-get install -y bison
+    apt-get install -y gdb
+    aptitude build-dep -y ruby1.9.1
+
+    # Install Tcl
+    curl -sSL -O http://prdownloads.sourceforge.net/tcl/tcl8.6.3-src.tar.gz
+    gunzip < tcl8.6.3-src.tar.gz | tar xvf -
+    cd tcl8.6.3/unix
+    ./configure
+    make
+    make install
+    cd ../..
+    rm -rf tcl*
+
+    # Install Tk
+    curl -sSL -O http://prdownloads.sourceforge.net/tcl/tk8.6.3-src.tar.gz
+    gunzip < tk8.6.3-src.tar.gz | tar xvf -
+    cd tk8.6.3/unix
+    ./configure
+    make
+    make install
+    cd ../..
+    rm -rf tk*
+
+    # Configure for build
+    su - vagrant -c "mkdir ~/build"
+    [ -f /vagrant/configure ] || { cd /vagrant && su - vagrant -c autoconf; }
+    su - vagrant -c "cd ~/build && /vagrant/configure"
+  SHELL
+
+  # Usage instructions that will be displayed whenever 'vagrant up' completes.
+  config.vm.post_up_message = <<-USAGE_INSTRUCTIONS
+  Helpful developer information can be found at https://bugs.ruby-lang.org/projects/ruby/wiki/DeveloperHowto
+
+  To access the MRI Ruby development virtual machine:
+
+    $ vagrant ssh
+    vagrant@vagrant-ubuntu-trusty-64:~$
+
+  To build ruby:
+
+    vagrant@vagrant-ubuntu-trusty-64:~$ cd ~/build
+    vagrant@vagrant-ubuntu-trusty-64:~$ make
+
+  To run MRI tests:
+
+    vagrant@vagrant-ubuntu-trusty-64:~$ cd ~/build
+    vagrant@vagrant-ubuntu-trusty-64:~$ make test-all
+
+  To update RubySpec tests:
+
+    vagrant@vagrant-ubuntu-trusty-64:~$ cd ~/build
+    vagrant@vagrant-ubuntu-trusty-64:~$ make update-rubyspec
+
+  To run RubySpec tests:
+
+    vagrant@vagrant-ubuntu-trusty-64:~$ cd ~/build
+    vagrant@vagrant-ubuntu-trusty-64:~$ make test-rubyspec
+
+  USAGE_INSTRUCTIONS
+end
diff --git a/vagrant.md b/vagrant.md
new file mode 100644
index 0000000..f3205de
--- /dev/null
+++ b/vagrant.md
@@ -0,0 +1,24 @@
+# Ruby Contributor Vagrant Guide
+
+The following instructions will help you quickly get an MRI Ruby development environment ready for contributing in short order.
+
+### Getting Started
+
+1. Install Git: http://git-scm.com/downloads (or [GitHub for Windows](http://windows.github.com/) if you want a GUI)
+2. Install VirtualBox: https://www.virtualbox.org/wiki/Downloads
+3. Install Vagrant: https://www.vagrantup.com/
+4. Open a terminal
+5. Clone the project: `git clone https://github.com/ruby/ruby.git`
+6. Enter the project directory: `cd ruby`
+
+### Setting Up Vagrant
+
+Build the Vagrant development environment by entering the following command:
+```
+vagrant up
+```
+
+The first time this command is ran will take a while because the VM image will need to download.
+
+Follow the directions at the end of the installation to begin contributing.
+