As a result of increased national emphasis on preparing future faculty in science, technology, engineering, and mathematics (STEM) to teach undergraduates, more research universities offer teaching development (TD) programs to doctoral students who aspire to academic careers. Using social cognitive career theory, we examine the effects of these programs on early-career STEM scholars' sense of self-efficacy as postsecondary teachers. In 2011, a survey questionnaire was administered to 2,156 people who in 2009 were doctoral students in STEM departments at three U.S. research universities; 1,445 responded (67%). Regression analysis revealed positive relationships between participation in TD and participants' college teaching self-efficacy, and positive interaction effects for women STEM doctoral students. The paper discusses implications for doctoral students, faculty advisors, and TD programs. The following are appended: (1) Variable Descriptions; and (2) Tables.