The focus of this paper is the effect of teachers' expectations for their students on their own behavior, on the classroom environment, and on learning. Literature is reviewed and integrated, and an assessment system for matching individual students with learning environments is presented. Section one reviews literature on the following topics: the relationship of teacher expectations to school effectiveness; the formation, communication, and effects of teachers' varying expectations; and the status of research on teachers' expectations and teachers' attitudes and perceptions concerning their students. Section two, drawing upon pertinent literature, advances the concept of behavioral ecology as a guide to analyzing the behavioral demands of the environment (including teacher expectations) and their relationship to affected individuals. Section three reviews an environmental assessment system, Assessment for Integration into Mainstream Settings (AIMS), which was designed for use with handicapped students but which may be applicable to others. AIMS identifies behavioral demands of classrooms and assesses child behavior relative to these demands and thus the child's adjustment to teachers and peers. The system's four instruments and results from tests of the system are described. Following a brief conclusion are an 11-page bibliography, a sample AIMS instrument, and two tables of data. (MCG)