Traditionally, the compilation of data-parallel languages is targeted to low-level runtime environments: abstract processors are mapped onto static system processes, which directly address the low-level IPC library. Alternatively, we propose to map each HPF abstract processor onto a ``lightweight process'' (thread) which can be freely migrated between nodes together with the data it manages, under the supervision of some external scheduler. We discuss the pros and cons of such an approach and the facilities which must be provided by the multithreaded runtime. We describe a prototype HPF compiler built along these lines, based on the Adaptor HPF compiler and the PM2 multithreaded runtime environment.