. We present an approach to reasoning about actor programs based on temporal logic. This formal framework allows more sophisticated abstraction mechanisms to be introduced into actor specifications. Such mechanisms turn out to be a major prerequisite for the use of actor systems in large-scale applications. 1 Temporal logic for actor computations Actor systems  have been developed as a convenient vehicle for combining concurrency and object-oriented programming principles. The spectrum of work being done ranges from hardware implementations of actor systems [15,21] over various actor programming languages  to semantic specifications of the actor computation model --- either operational or denotational ones [3,8]. Usually, formal considerations of actors systems rely upon quite primitive, low-level constructs that can hardly be applied to complex real-world problems. Looking for a more appropriate formal framework which allows for enhanced abstraction mechanisms, temporal lo..