Through Grid and Cloud computing, the importance of distributed computing has risen dramatically in recent years, increasing the computational power available to a widening audience of scientific and commercial users. Gains in computing power have caused a drastic increase in the volume of data produced by users, requiring new research on improved management and access to distributed data. These gains also drive the need for efficient scheduling and leasing of computational resources and for adapting current work in machine virtualization to a distributed context. These research directions require the development and evaluation of new models for computational, communication, and storage costs, but existing infrastructure makes model evaluation difficult or impossible, since they are in constant use by other researchers. This project addresses these concerns by providing a diverse group of researchers with a Distributed Research Testbed (DiRT) on which to develop and evaluate new technologies. The clusters making up the testbed are located at the University of Chicago, the University of Florida, the University of Hawai?i, the University of Notre Dame, and the University of Mississippi. Unlike working grid environments, we have complete low-level control of the hardware and complete knowledge of where the data and computation are located. We will use the testbed to address problems faced today by the growing number of users of distributed computing. Because high performance computing is essential to the conduct of modern science, this project will have significant impact on research and education in a a wide variety of scientific disciplines.