Multithreaded execution models attempt to combine some aspects of dataflow-like execution with von Neumann model execution, with the objective of masking the latency of inter-processor communications and remote memory accesses in multiprocessors. An important issue in the analysis and evaluation of multithreaded execution is the design and performance of the storage hierarchy. Because of the sequential execution of threads, the locality of access within an executing thread can be exploited using registers and cache. At the inter-thread level, however, the locality of accesses to memory and its effect on the cache is not yet well understood. Two storage hierarchy models, that attempt to capture and exploit this locality, are described and evaluated in this paper.