The observations of a teacher educator who spent a semester teaching in a mainstreamed elementary classroom are recorded in this monograph. Case studies of students form the framework for the consideration of the broader implications and problems involved in mainstreaming. Illustrative classroom practices are offered to clarify such concepts as teaching children to value diversity, managing the classroom environment, adapting curriculum to special needs, and individualizing instruction. Four teacher competencies are identified as essential for teachers of mainstreamed handicapped children: (1) the ability to teach children to value individual differences; (2) individual and group management techniques which create a positive learning climate and allow children to spend time on tasks; (3) the ability to assess needs, provide appropriate instruction, and keep records on pupil progress toward established objectives; and (4) the ability to modify curriculum when it is necessary to meet individual student needs. (JD)