The primary purpose of this investigation was to develop and test an assessment center for prospective cooperating teachers to be used as an alternative to a student teacher supervision workshop for certifying school-based student teacher supervisors (cooperating teachers). The assessment center components included a forty item paper-and-pencil test of knowledge of instructional supervision, and a set of exercises in which subjects evaluated a set of instructional plans and evaluated a teacher's performance in a videotaped teaching episode;One group of subjects participated in the student teacher supervision workshop at California Polytechnic State University and then took part in the assessment center. Another group participated in the assessment center without the training from CPSU. Subjects' scores on the knowledge test were compared, as were their ratings of the instructional plan and the teacher's performance in the simulation. Results were disaggregated by group, gender, and level of employment (elementary teachers, secondary teachers, administrators);There were no significant differences found between groups or with respect to gender or level of employment for any of the assessment center components taken as a whole. There were some differences in the ratings of the teacher's instructional plan and performance on a few of the individual criteria, when disaggregated by level of employment;It was concluded that the assessment center is a feasible alternative for training personnel in instructional supervision in a conventional program.