Modula is a new programming language for implementing dedicated, parallel systems. Following a systematic design technique, this paper illustrates the use of Modula for the design of a message switching communication system. A message switching system poses a number of interesting. problems: a high degree of concurrent activity exists, a variety of I/O devices need to be controlled, messages can have multiple destinations, and messages can be preempted. The strengths and weaknesses of Modula with respect to these specific problems and its utility as a general purpose language are evaluated.