Abstract In the paper software tools are described which allow structured concurrent programming of loosely coupled distributed systems with common memory. Sequential program parts and all structures serving for control, communication and synchronization of these parts are strictly separated. The PARC (= par allel c onstruct) concept, derived from Dijkstra's guarded commands, is extended towards language structures which allow concurrent and sequential programming on different layers. The construction method strictly reduces critical sections and simplifies programming of error recovery mechanisms. Thus real-time behaviour of systems is improved. The description of the concept is supplemented by examples and an implementation model.