This study tested the Systematic Distortion Hypothesis by examining the factorial validity of student ratings of university teaching. Factorial validity is defined as the degree to which covariance among judged traits resembles the actual or true covariation of observable behaviors underlying these traits. Although many studies have examined the factorial validity of ratings, results are inconsistent. The present study used a more complete methodology to address some of the limitations of previous studies. Student ratings of teaching and measurements of actual teaching behaviors were obtained for 32 instructors. Student ratings were compared to frequency counts of actual teaching behaviors obtained from videotape and to students' similarity judgments of teacher characteristics. It was found, first, that the structure of student ratings showed a moderately strong relation to the structure of actual behaviors, and a somewhat stronger relation to the structure of conceptual associations; and second, that the effects of systematic distortion were more pronounced for low-inference student ratings than for high-inference ratings.