The purpose of this study was to assess the sources of award-wining research professors' (six women; six men) teaching self-efficacy through the framework of Bandura's (1986) social cognitive theory. Semi-structured interviews revealed that mastery experiences and social persuasions were particularly influential sources of self-efficacy and that these sources tended to be closely related. Professors reported that their self-efficacy had generally stabilized within their first few years of assuming a tenure-track position. Participants framed negative events in adaptive ways that had little cost to their teaching self-efficacy. (Contains 3 tables.)