An extensive search of the literature on clinical supervision yielded 29 research studies and 3 works in progress. Studies using comparative measures conducted in K-12 school settings with inservice not preservice personnel were selected. These were grouped into four areas: attitudes toward supervision, effects of training, characteristics of school personnel, and student achievement. While many of the studies reported findings that tended to favor clinical supervision over other supervision practices, these findings were generally not statistically significant. The discussion presented issues involving difficulties in findings references and obtaining copies of research studies, the limited scope and methodological problems in the studies, and the design problems inherent in field-based studies. (Author)