This paper dttcasse» a language and associated environment for building rule-based programs. The language and environment are encapsulated in a system we call ORBS (Oregon Rule Based System). In tune with this conference, oar focus will be on the interplay between language and environment design. However, we will broaden this somewhat to include design constraints placed by our program development model1 as well Instead of attempting a complete design rationalization of ORBS, we will concentrate on design decisions that highlight the coupling between language, environment, and development model.