Issues pertaining to the validity of student ratings of teaching effectiveness are considered, and research results are evaluated. The following extraneous variables that affect student ratings but are not under the control or influence of the teacher are examined: class size, initial student motivation, academic field, teacher characteristics, and situational leniency. If effective teaching is defined by student progress on teacher defined goals, some measure of that progress is needed. The following measures are assessed: grades, achievement tests, and student self-report. Based on the research, it is suggested that student ratings are adequately reliable and relevant measures to be included in teacher evaluation procedures. Evidence is cited to indicate that student ratings are strongly related to the ratings of teacher effectiveness by administrators, peers, and the teachers themselves. It was also found that students can make fine distinctions along a number of dimensions of teacher effectiveness. It was also found that student ratings by themselves are not very helpful to teachers seeking to improve instruction. However, some student rating systems (notably IDEA) provide interpretative assistance that can enhance the usefulness of student ratings for diagnosis. It is also possible that instructional development specialists can provide help to teachers in translating the information from student ratings into appropriate changes in teacher behavior. A bibliography is included. (SW)