Abstract: This year-long leadership development program was designed to enhance the cognitive, affective, and behavioral dimensions of leadership self-efficacy of HBCU STEM leaders to broaden the participation of African American undergraduates in STEM. Learning outcomes guided the development of curricular resources including on-line learning, multi-day residencies, individual leadership assessment, and an action learning project. Mixed-method evaluation showed significant gains on all learning outcomes, with the highest post-test ratings in application of leadership skills, leading faculty in STEM teaching strategies, leading instructional innovation, developing programs for broadening participation in STEM, and increasing campus awareness of national challenges related to STEM.