For many real-time applications (e.g. Command, Control, and Communications), parallel computers offer a natural computing platform. However, very little attention has been paid to the specification requirements of real-time systems implemented on parallel machines. Towards this end, we propose a specification language PRETSEL (Parallel REal-Time SpEcification Language). The PRETSEL specification language is based on a traditional two-level view of parallel computing whereby a parallel computation is viewed as a collection of interacting (data) parallel algorithms. This view is naturally reflected in PRETSEL syntax where at the lower level various constructs are provided for the specification of a data-parallel real-time algorithm (data-parallelism). At the upper level another set of constructs is provided to combine such tasks in a variety of way (task-parallelism). Furthermore, the PRETSEL language allowsfor the specification of performance requirements. PRETSEL is currently being evaluated for real-time avionics applicaitons. In this paper we describe the sysntax and operational semantics of PRETSEL and establish results relating the functional and the temporal behaviors.