diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1ca1f19..afa54a1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,7 +21,9 @@ Unfortunately it comes with a couple of BREAKING changes:
   contract expects the event type to be a fully classified
   class name (subclass of Event) and will attempt to factor
   one. The second argument is no longer a world (Hash) but
-  a context instance to attach to the event (a dup is made).
+  a context instance to attach to the event. A context fork
+  is made, using the event context data passed through the
+  Context h_factory (if event contains context info).
 
 * `Startback::Engine` constructor takes ServerEngine options
   under a `:server_engine` key (was the options themselves).
diff --git a/lib/startback/context.rb b/lib/startback/context.rb
index 02fc713..cfc46d9 100644
--- a/lib/startback/context.rb
+++ b/lib/startback/context.rb
@@ -112,6 +112,13 @@ def to_json(*args, &bl)
       to_h.to_json(*args, &bl)
     end
 
+    def fork(h = nil)
+      dup.tap{|duped|
+        self.class.h_factor!(duped, h) if h
+        yield(duped) if block_given?
+      }
+    end
+
     def dup
       super.tap{|c|
         c.send(:clean_factored!)
diff --git a/lib/startback/event.rb b/lib/startback/event.rb
index 1c9e3f2..4f3a359 100644
--- a/lib/startback/event.rb
+++ b/lib/startback/event.rb
@@ -23,6 +23,7 @@ def initialize(type, data, context = nil)
     def self.json(src, context)
       parsed = JSON.parse(src)
       klass = Kernel.const_get(parsed['type'])
+      context = context.fork(parsed['context']) if context
       klass.new(parsed['type'], parsed['data'], context)
     end
 
diff --git a/lib/startback/event/engine.rb b/lib/startback/event/engine.rb
index b0db797..7355cb1 100644
--- a/lib/startback/event/engine.rb
+++ b/lib/startback/event/engine.rb
@@ -86,7 +86,7 @@ def create_agents
       end
 
       def factor_event(event_data)
-        Event.json(event_data, context.dup)
+        Event.json(event_data, context)
       end
 
       class Runner
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 78237c3..fc7ced6 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -11,6 +11,26 @@ module SpecHelpers
   c.include SpecHelpers
 end
 
+class SubContext < Startback::Context
+  attr_accessor :foo
+  h_factory do |c,h|
+    c.foo = h["foo"]
+  end
+  h_dump do |h|
+    h.merge!("foo" => foo)
+  end
+end
+
+class SubContext
+  attr_accessor :bar
+  h_factory do |c,h|
+    c.bar = h["bar"]
+  end
+  h_dump do |h|
+    h.merge!("bar" => bar)
+  end
+end
+
 class User
   class Changed < Startback::Event
   end
diff --git a/spec/unit/context/test_dup.rb b/spec/unit/context/test_dup.rb
index 8f02ff7..9bdc771 100644
--- a/spec/unit/context/test_dup.rb
+++ b/spec/unit/context/test_dup.rb
@@ -3,12 +3,8 @@
 module Startback
   describe Context, "dup" do
 
-    class Subcontext < Context
-      attr_accessor :foo
-    end
-
     let(:context) {
-      Subcontext.new.tap{|s| s.foo = "bar" }
+      SubContext.new.tap{|s| s.foo = "bar" }
     }
 
     class ContextRelatedAbstraction
@@ -27,7 +23,7 @@ def initialize(context)
         expect(x).not_to be(context)
       }
       expect(seen).to be(got)
-      expect(got).to be_a(Subcontext)
+      expect(got).to be_a(SubContext)
       expect(got).not_to be(context)
       expect(got.foo).to eql("bar")
     end
@@ -43,4 +39,4 @@ def initialize(context)
     end
 
   end
-end
\ No newline at end of file
+end
diff --git a/spec/unit/context/test_fork.rb b/spec/unit/context/test_fork.rb
new file mode 100644
index 0000000..940c618
--- /dev/null
+++ b/spec/unit/context/test_fork.rb
@@ -0,0 +1,38 @@
+require 'spec_helper'
+
+module Startback
+  describe Context, "fork" do
+
+    it 'is a simple dup without args' do
+      context = SubContext.new
+      context.foo = ['hello']
+
+      forked = context.fork
+      puts "Forked: #{forked.inspect}"
+      expect(fork).not_to be(context)
+      expect(forked.foo).to eql(['hello'])
+      expect(forked.foo).to be(context.foo)
+    end
+
+    it 'yields the context if a block is provided' do
+      context = SubContext.new
+
+      seen = false
+      context.fork({ 'foo' => 'hello' }) do |forked|
+        expect(fork).not_to be(context)
+        expect(forked.foo).to eql('hello')
+        seen = true
+      end
+      expect(seen).to eql(true)
+    end
+
+    it 'uses the factory on the hash provided' do
+      context = SubContext.new
+
+      forked = context.fork({ 'foo' => 'hello' })
+      expect(fork).not_to be(context)
+      expect(forked.foo).to eql('hello')
+    end
+
+  end
+end
diff --git a/spec/unit/context/test_h_factory.rb b/spec/unit/context/test_h_factory.rb
index f45ab19..180bdcc 100644
--- a/spec/unit/context/test_h_factory.rb
+++ b/spec/unit/context/test_h_factory.rb
@@ -7,26 +7,6 @@ module Startback
       expect(Context.new.to_json).to eql("{}")
     end
 
-    class SubContext < Context
-      attr_accessor :foo
-      h_factory do |c,h|
-        c.foo = h["foo"]
-      end
-      h_dump do |h|
-        h.merge!("foo" => foo)
-      end
-    end
-
-    class SubContext
-      attr_accessor :bar
-      h_factory do |c,h|
-        c.bar = h["bar"]
-      end
-      h_dump do |h|
-        h.merge!("bar" => bar)
-      end
-    end
-
     it 'allows installing factories' do
       expect(Context.h_factories).to be_empty
       expect(SubContext.h_factories.size).to eql(2)
diff --git a/spec/unit/test_event.rb b/spec/unit/test_event.rb
index 87ffbf6..9d4ea7c 100644
--- a/spec/unit/test_event.rb
+++ b/spec/unit/test_event.rb
@@ -50,8 +50,11 @@ module Startback
       end
 
       it 'accepts an explicit context as second argument' do
-        evt = Event.json(JSON_SRC, 12)
-        expect(evt.context).to eql(12)
+        c = SubContext.new.tap{|x| x.foo = 'hello' }
+        evt = Event.json(JSON_SRC, c)
+        expect(evt.context).not_to be(c)
+        expect(evt.context).to be_a(SubContext)
+        expect(evt.context.foo).to eql('hello')
       end
     end