Distributed systems are an alternative to shared-memory multiprocessors for the execution of parallel applications.Panda is a run-time system that provides architectural support for efficient parallel and distributed programming. It supplies fast user-level threads and a means for transparent and coordinated sharing of objects across a homogeneous network. The paper motivates the major architectural choices that guided our design. The problem of sharing data in a distributed environment is discussed, and the performance of the mechanisms provided by thePanda prototype implementation is assessed.