Women are sparsely represented in leadership in academic science, technology, engineering, mathematics, and medicine (STEMM). Cultural stereotypes about men, women, and leaders influence the attitudes, judgments, and decisions that others make about women and the choices women make for themselves. Multilevel interventions are needed to counteract the impact of these pervasive and easily activated stereotypes, which conspire in multiple ways to constrain women's entry, persistence, and advancement in academic STEMM. We describe an individual-level educational intervention. Using the transtheoretical model of behavioral change as a framework, we assessed the success of a semester course on increasing women's leadership self-efficacy for the first three cohorts of course participants (n = 30). Pre/post questionnaires showed gains in leadership self-efficacy, personal mastery, and self-esteem, and decreases in perceived constraints. Qualitative text analysis of weekly journals indicated increasing leadership self-efficacy as course participants applied course information and integrated strategies to mitigate the impact of societal stereotypes into their own leadership practices. Follow-up queries of the first two cohorts supported the enduring value of course participation. We conclude that providing strategies to recognize and mitigate the impact of gender stereotypes is effective in increasing leadership self-efficacy in women at early stages of academic STEMM careers. (Contains 3 tables and 1 figure.)