diff --git a/README.md b/README.md
index b57dd9392..5774f8d50 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,7 @@ The design goals of this gem are:
   agent in [F#](http://msdn.microsoft.com/en-us/library/ee370357.aspx)
 * [Dataflow](https://github.com/jdantonio/concurrent-ruby/blob/master/md/dataflow.md) loosely based on the syntax of Akka and Habanero Java
 * [MVar](https://github.com/jdantonio/concurrent-ruby/blob/master/md/mvar.md) inspired by Haskell
+* [Thread local variables](https://github.com/jdantonio/concurrent-ruby/blob/master/md/threadlocalvar.md) with default value
 
 ### Semantic Versioning
 
diff --git a/lib/concurrent.rb b/lib/concurrent.rb
index 14ecbc3fd..352d22d58 100644
--- a/lib/concurrent.rb
+++ b/lib/concurrent.rb
@@ -23,6 +23,7 @@
 require 'concurrent/scheduled_task'
 require 'concurrent/stoppable'
 require 'concurrent/supervisor'
+require 'concurrent/threadlocalvar'
 require 'concurrent/timer_task'
 require 'concurrent/utilities'
 
diff --git a/lib/concurrent/threadlocalvar.rb b/lib/concurrent/threadlocalvar.rb
new file mode 100644
index 000000000..65cd3ddc9
--- /dev/null
+++ b/lib/concurrent/threadlocalvar.rb
@@ -0,0 +1,115 @@
+module Concurrent
+
+  module ThreadLocalSymbolAllocator
+
+    protected
+
+    def allocate_symbol
+      # Warning: this will space leak if you create ThreadLocalVars in a loop - not sure what to do about it
+      @symbol = "thread_local_symbol_#{self.object_id}_#{Time.now.hash}".to_sym
+    end
+
+  end
+
+  module ThreadLocalOldStorage
+
+    include ThreadLocalSymbolAllocator
+
+    protected
+
+    def allocate_storage
+      allocate_symbol
+    end
+
+    def get
+      Thread.current[@symbol]
+    end
+
+    def set(value)
+      Thread.current[@symbol] = value
+    end
+
+  end
+
+  module ThreadLocalNewStorage
+
+    include ThreadLocalSymbolAllocator
+
+    protected
+
+    def allocate_storage
+      allocate_symbol
+    end
+
+    def get
+      Thread.current.thread_variable_get(@symbol)
+    end
+
+    def set(value)
+      Thread.current.thread_variable_set(@symbol, value)
+    end
+
+  end
+
+  module ThreadLocalJavaStorage
+
+    protected
+
+    def allocate_storage
+      @var = java.lang.ThreadLocal.new
+    end
+
+    def get
+      @var.get
+    end
+
+    def set(value)
+      @var.set(value)
+    end
+
+  end
+
+  class ThreadLocalVar
+
+    NIL_SENTINEL = Object.new
+
+    if defined? java.lang.ThreadLocal.new
+      include ThreadLocalJavaStorage
+    elsif Thread.current.respond_to?(:thread_variable_set)
+      include ThreadLocalNewStorage
+    else
+      include ThreadLocalOldStorage
+    end
+
+    def initialize(default = nil)
+      @default = default
+      allocate_storage
+    end
+
+    def value
+      value = get
+
+      if value.nil?
+        @default
+      elsif value == NIL_SENTINEL
+        nil
+      else
+        value
+      end
+    end
+
+    def value=(value)
+      if value.nil?
+        stored_value = NIL_SENTINEL
+      else
+        stored_value = value
+      end
+
+      set stored_value
+
+      value
+    end
+
+  end
+
+end
diff --git a/md/threadlocalvar.md b/md/threadlocalvar.md
new file mode 100644
index 000000000..62aae5968
--- /dev/null
+++ b/md/threadlocalvar.md
@@ -0,0 +1,33 @@
+# Thread local variables
+
+A `ThreadLocalVar` is a variable where the value is different for each thread.
+Each variable may have a default value, but when you modify the variable only
+the current thread will ever see that change.
+
+```ruby
+v = ThreadLocalVar.new(14)
+v.value #=> 14
+v.value = 2
+v.value #=> 2
+```
+
+```ruby
+v = ThreadLocalVar.new(14)
+
+t1 = Thread.new do
+  v.value #=> 14
+  v.value = 1
+  v.value #=> 1
+end
+
+t2 = Thread.new do
+  v.value #=> 14
+  v.value = 2
+  v.value #=> 2
+end
+
+v.value #=> 14
+```
+
+Note that except on JRuby, `ThreadLocalVar` needs to allocate a unique symbol
+for each instance. This may lead to a space leak.
diff --git a/spec/concurrent/threadlocalvar_spec.rb b/spec/concurrent/threadlocalvar_spec.rb
new file mode 100644
index 000000000..9cbaafa82
--- /dev/null
+++ b/spec/concurrent/threadlocalvar_spec.rb
@@ -0,0 +1,97 @@
+require 'spec_helper'
+
+module Concurrent
+
+  describe Future do
+
+    context '#initialize' do
+
+      it 'can set an initial value' do
+        v = ThreadLocalVar.new(14)
+        v.value.should eq 14
+      end
+
+      it 'sets nil as a default initial value' do
+        v = ThreadLocalVar.new
+        v.value.should be_nil
+      end
+
+      it 'sets the same initial value for all threads' do
+        v = ThreadLocalVar.new(14)
+        t1 = Thread.new { v.value }
+        t2 = Thread.new { v.value }
+        t1.value.should eq 14
+        t2.value.should eq 14
+      end
+
+    end
+
+    context '#value' do
+
+      it 'returns the current value' do
+        v = ThreadLocalVar.new(14)
+        v.value.should eq 14
+      end
+
+      it 'returns the value after modification' do
+        v = ThreadLocalVar.new(14)
+        v.value = 2
+        v.value.should eq 2
+      end
+
+    end
+
+    context '#value=' do
+
+      it 'sets a new value' do
+        v = ThreadLocalVar.new(14)
+        v.value = 2
+        v.value.should eq 2
+      end
+
+      it 'returns the new value' do
+        v = ThreadLocalVar.new(14)
+        (v.value = 2).should eq 2
+      end
+
+      it 'does not modify the initial value for other threads' do
+        v = ThreadLocalVar.new(14)
+        v.value = 2
+        t = Thread.new { v.value }
+        t.value.should eq 14
+      end
+
+      it 'does not modify the value for other threads' do
+        v = ThreadLocalVar.new(14)
+        v.value = 2
+
+        b1 = CountDownLatch.new(2)
+        b2 = CountDownLatch.new(2)
+
+        t1 = Thread.new do
+          b1.count_down
+          b1.wait
+          v.value = 1
+          b2.count_down
+          b2.wait
+          v.value
+        end
+        
+        t2 = Thread.new do
+          b1.count_down
+          b1.wait
+          v.value = 2
+          b2.count_down
+          b2.wait
+          v.value
+        end
+        
+        t1.value.should eq 1
+        t2.value.should eq 2
+      end
+
+    end
+
+  end
+
+end