A frequently used method of measuring teaching effectiveness is the anonymous student rating of the instructor at the end of a grading period. The validity of these ratings for faculty personnel decisions has been a source of controversy. The purposes of this study were to examine the differences in teaching effectiveness between selected courses; investigate the effects of course type and course level on measures of teaching effectiveness, as well as possible interactions between type and level; and examine the differences between measures of effectiveness and their reliability. Data consisted of students' evaluations of undergraduate and graduate mathematics course instructors. Analysis of variance was used to compare the mean ratings from 20 mathematics courses in the study. Results indicated that the particular course, its type, and its level are important factors to consider when using student evaluations of teaching performance. (DWH)