There is an increasing interest in the study of software architectures; however, it still unclear which kind of formalisms and techniques should be used in their design. We study the suitability of a rule‐based, parallel logic language in the specification of the architecture of a complex software system, i.e. a software development environment. We have used as a case study SMILE, an environment for programming‐in‐the‐large. Because of the declarative, concurrent and object‐oriented features of parallel logic programming, we have been able to design a software architecture that emphasizes the dynamics of co‐ordination inside the software development environment. The result of this experience shows the usefulness and some weaknesses of logic languages for specifying and prototyping the software architecture of a distributed interactive system.