If you are like me, you may have been surprised when you read the MSDN documentation for System.Activities.Statement... A Parallel activity operates by simultaneously scheduling each Activity in its Branches collection at the start. It completes when all of its Branches complete or when its CompletionCondition property evaluates to true. While all the Activity objects run asynchronously, they do not execute on separate threads, so each successive activity only executes when the previously ......