Clinical supervisors have important, but perhaps poorly understood, roles involving quality assessment and improvement, and datekeeping. Supervisors provide evaluation and certification of trainees attesting to their qualifications to continue in their training and performance as mental health service providers. However, bias in supervisory evaluations is a pervasive problem as a training issue in professional psychology. Supervisors (n = 62) at APA-accredited clinical psychology internships estimated rates of leniency, central tendency, and strictness bias among supervisors in general and their own bias in evaluations and letters of reference. The implications of bias in supervisory evaluation are discussed. Potential steps to limit supervisors' bias and increase accountability are recommended.