Summary The extent of the relationships of assumed and actual student-instructor attitudinal similarity to instructor and course evaluations was investigated in a sample comprising 409 undergraduates and 14 instructors involved in 21 divisions of an educational psychology course. The hypothesized positive correlation between assumed similarity and attraction to the instructor was confirmed (p < .001). Several other instructor and course evaluation variables also evidenced moderately positive correlations with assumed similarity, whereas there appeared to be little evidence of any relationships existing between actual similarity and these evaluation variables. These findings were interpreted as evidence for the presence of Newcomb's “strain toward symmetry” in students' evaluative responses to instructors.