The present study investigated the effectiveness of cooperating teachers at four sites where several of the factors associated with effective supervision were present. In the first stage of the research, information was gathered through interviews and artifact collection about cooperating teachers' supervisory preparation, practices, and perceptions. In the second stage of the research, researchers used ex post facto methods to used ex post facto methods to identify background and intervention factors associated with their effectiveness levels. 13 pairs of cooperating-teacher-student-teacher from four sites participated in the study.