— Large-scale applications, in the form of workflows, may require the coordinated usage of resources spreading across multiple administrative domains. Scalable solutions need a decentralized approach to coordinate the execution of such workflows. At runtime, adjustments to the workflow execution plan may be required to meet Quality of Service objectives. In this paper, we provide a decentralized execution approach to large-scale workflows on different resource domains. We also provide a low overhead, decentralized runtime adaptation mechanism to improve the performance of the system. Our prototype implementation is based on standard Condor DAGMan workflow execution engine and does not require any modifications to Condor or its underlying system.