Within this article, the researchers present the design, implementation, and evaluation of a pilot of a virtual peer mentoring training program for racial and ethnic minority women peer mentors within STEM programs at two historically black institutions. The design, usefulness, and usability of the training program are explored, and the influence of participation in the training program on mentors' self-efficacy, mentoring competencies, and persistence in STEM. The results demonstrate that racial and ethnic minority women peer mentors participating in the program increased their STEM self-efficacy, and, in turn, their mentoring competencies and intent to graduate from a STEM program. In addition to these results, lessons learned about the program and its design, including usefulness and usability, and implementation are shared.