A representative sample of current research investigating ecological variables in classrooms is reviewed in this paper. Empirically-based recommendations for classroom arrangement and suggested areas of research which might be beneficial to the development of prescriptive guidelines for preschool classrooms for handicapped children are provided. The content of the review has been organized into five major divisions: (1) adults in the classroom, (2) the grouping of children within the classroom, (3) architectual variables, (4) scheduling, and (5) arrangement of materials in the classroom. It is concluded that, in general, current research recommendations for facilities for handicapped children do not appear to be based on empirical findings about effects of environmental variables on child or teacher behavior. It is argued that programatic research in this area is needed to better define the effects of teacher/child ratios, material choice and arrangements, child groupings, scheduling, and architectural arrangements on the behavior of handicapped children in preschool classrooms. (Author/MP)