One key to transforming undergraduate STEM education is better preparation of doctoral students who will become STEM faculty for their essential role as teachers and mentors. Over the past decade, significant time and resources have been invested in the development of numerous teaching-related professional development programs aimed at enhancing traditional doctoral training at research universities. However, little is known about the effectiveness of these programs. This research study is exploring a critical yet understudied juncture of graduate and undergraduate education: the preparation of future faculty for their pivotal role as teachers of undergraduates who will become the next generation of scientists, engineers, mathematicians, and science and math teachers. This Phase III Project is building on four years of research supported by the NSF-funded Center for the Integration of Research, Teaching, and Learning (CIRTL). It is a 5-year, multi-institutional study that is examining the short- and long-term effects of future-faculty professional development (FFPD) on STEM doctoral students and their early-career performance. The study is addressing six research questions: (1) What are the general characteristics of FFPD programs, and which characteristics are most strongly correlated with positive and negative participant outcomes? (2) What characteristics distinguish FFPD participants from non-participants, and what encourages and discourages participation? (3) What do doctoral students gain from FFPD programs that helps prepare them for diverse academic careers? (4) What influence does participation in FFPD programs have on the kinds of careers that STEM PhDs choose? (5) Does participation in FFPD have impact on indicators of early career performance? (6) What degree of investment in FFPD must a doctoral student make, and for what length of time, to receive modest but significant benefits? The study is using a longitudinal mixed-methods design that is following two groups of STEM doctoral students from three research universities over five years. One group of doctoral students who have participated in FFPD programs will be interviewed a total of three times: at the end of their doctoral program; soon after taking their first academic job; and in the third year of their job. A second group comprised of a large randomly-selected sample of STEM doctoral students including both FFPD participants and non-participants will be surveyed in Years 1 and 5 of the study.