This paper reports on two studies in which the effectiveness of two types of student teacher supervisors was rated by cooperating teachers and by student teachers. The first study examined cooperating teachers' and student teachers' perceptions of specific performance aspects of university (college faculty) supervisors and of teaching assistants. The cooperating teachers and student teachers rated differences between the university supervisors and teaching assistants in terms of their helpfulness in developing the skills of student teachers. The performance differences between the two types of supervisors were seen by both the cooperating and the student teachers as minimal. The procedures in the second study were similar to those in the first. The qualifications of elementary teaching experience, elementary certification, and supervisory experience were tested as criteria for supervisor effectiveness. Both the cooperating and the student teachers found significant differences for supervisors with certification and previous supervisory experience; previous classroom experience was not perceived as a key to effective student teacher supervision. Data in the findings seem to raise questions about certain long-held beliefs about qualifications for effective student teacher supervision. Answers to the questionnaire, which gathered the test data from 318 cooperating teachers and 264 student teachers, are displayed in tabular form. (FG)