Using a qualitative approach, documents were reviewed and teachers, peer evaluators, instructional supervisors, and administrators were interviewed in order to evaluate the effectiveness of peer evaluation programs in three school districts. Specifically, this study examines peer involvement in the summative evaluation of teachers in three school districts: Sunnyside School District (California); Oceanview School District (New York); and Midtown Public Schools, an urban system in a large, midwestern city. The districts differed in size, socioeconomic status and length of involvement with a peer evaluation program, but all three gave high ratings to their own peer evaluation program. While one district used peer evaluation only at the secondary level, another focused on teacher remediation. The third district had a mandatory Teacher Development Program including a model career ladder, and peer evaluation for all new teachers. Three themes emerged as critically important in all three districts: professional involvement; collegial relationships; and blending of bureaucratic and professional authority. It was concluded that: (1) teacher involvement was beneficial in securing teacher commitment and in maximizing both teacher observation time and sources of expertise within a district; (2) decisions about the extent and form of peer evaluation should be made at the school district level; (3) teachers can be very effective peer evaluators, despite feelings of role conflict; and (4) combining teachers' and administrators' authority can provide checks and balances to the evaluation procedure and improve the validity of the results. (JGL)