The addition of reconfigurable hardware (FPGAs) to the nodes of Beowulf-style clusters has the potential to accelerate a variety of parallel applications through a combination of parallel programming and reconfigurable computing techniques. However, making efficient use of the computational resources available places a significant burden on the application developer due to the lack of support for reconfigurable computing and task heterogeneity in standard message-passing libraries. This paper describes Accessible Reconfigurable Computing (ARC), a metacomputing environment designed to address these issues. The architecture, implementation, and operation of the system are described in detail.