The authors define environmental simulation as the selection, manipulation and/or modification of any number and combination of the five senses to create an experience which simulates a real or imaginary environment. They see the goal of environmental simulation as producing affective-cognitive-psychomotor outcomes which can be set, modified, changed, or eliminated either before, during, or after the experience by an environmental designer, by the participants in the experience, or by both together. In order to test their assumptions they built and used a series of increasingly sophisticated "theaters" in which a total environment could be simulated. The prototype theater was a five-sided portable enclosure with a carpeted floor for seating. Slides were projected on each wall and appropriate sounds and odors were supplied. A paper tape control device was used to automatically sequence and advance the five slide projectors. Several larger versions of the theater were also developed. On the basis of their experience and of participants' comments they compiled some suggestions for improving the theater itself and the presentation of the sensory inputs. Some of the possibilities for using environmental simulation in the natural and social sciences, humanities, professional training, and in group settings are explored briefly. (JY)