The School Environment Inventory (SEI), an instrument for characterizing classroom environments, consists of 23 scales subsumed under five major headings: (a) curriculum, (b) predominant mode of teaching, (c) degree and mode of organization of teaching, (d) quality of teacher's relationship with children, and (e) characteristics of the physical environment. The inventory was designed to distinguish between primary grade classrooms in which the teacher's ideology and teaching methods varied from traditional to open and progressive, in order to meet the needs of the Differentiated Child Behavior Observation System. Because the SEI makes explicit some crucial teaching dimensions, it is expected to be useful as an independent instrument, not only for characterizing classroom environment in research studies, but also for training and supervising teachers and paraprofessionals. (Author)