The authors examine the relationship between students' locus of control and their evaluation of teaching in a traditional principles of economics course. Locus of control is a psychological construct that identifies an individual's beliefs about the degree of personal control that can be exercised over his or her environment. Students with an internal locus-of-control orientation accept responsibility for control over their environment whereas those with an external orientation believe that they have little control or power to affect personal outcomes. The authors entered students' Rotter scale scores derived from the standard instrument used to measure locus of control orientation into an empirical ordered probit model estimated to explain the determination of student evaluation of teaching scores. The results indicate that more internally oriented students had a greater probability of assigning above average evaluation marks with respect to instructor performance whereas more externally oriented students had a greater probability of assigning average and below average instructor evaluation marks. (Contains 12 endnotes.)