To many people, the term "clinical supervision" now means the Hunter Model, which involves monitoring of teachers' classroom behavior for usage of Hunter's essential elements of instruction, feedback of these results, reinforcement of desired practice, and a prescription for remediation of teachers' performance. In contrast, the Goldhammer-Cogan clinical supervision model involves the teacher in a collaborative process whereby both teacher and supervisor decide on observation objectives and changes in the teacher's classroom behavior following discussion of classroom observational data. Research relating to the implementation and results of these two models indicates that they are very different. This paper reviews that research in terms of: (1) effects of training; (2) model usage by administrators and teachers; (3) the relationship of clinical supervision to student academic achievement; (4) model implementation; and (5) model costs. (CB)