This design case describes the tensions and resolutions related to the iterative design of a virtual STEM peer mentoring program for White and Black, Indigenous, and People of Color (BIPOC) women in STEM study programs at Historically Black Colleges and Universities (HBCUs) and at Minority Serving Institutions (MSIs). Stakeholder feedback, along with a conceptual framework, including Tinto's Institutional Departure Model and Bandura's Theory of Self-Efficacy, guided the design work. The second iteration featured eight self-paced, eLearning modules designed to be completed as one per week in conjunction with asynchronous and synchronous communications with program peers and faculty facilitators. The design goals focused on the self-paced modules and resolved content presentation, case videos, practice, and reflection issues. The case highlights the intersection of new design elements with Bandura's (1977) four sources of self-efficacy: social persuasion, vicarious experiences, performance accomplishments, and psychological response.