The limited number of women persisting in STEM degree programs and pursuing STEM careers is concerning, particularly when one considers the absence of minority women in this field. One way of addressing this issue is to explore avenues that build women's STEM self-efficacy. Providing connections with other more experienced women involved in STEM through e-mentoring is one approach that could give women the support and experience they need to feel confident in their ability to succeed in STEM fields. Highly qualified mentors are a key component in the mentoring process and, therefore, need focused training that prepares them to support mentees. As such, this multi-site case study explored how self-efficacy and persistence can be facilitated through e-mentor training. A short survey, along with observations, focus groups, and interviews were conducted to gather the experiences of stakeholders participating in a STEM e-mentor training program across two historically Black colleges and universities (HBCUs). These methods looked specifically at mentors' self-efficacy and persistence as well as what could be learned about the potential impact of online mentor training programs. Results of the pre and post-test survey demonstrated that the training program promoted an increase in self-efficacy, mentorship skill development, and STEM persistence. Although mentors had unique experiences across the two sites, all five mentors shared that their experience in the e-mentoring training was positive and that the content of the training was beneficial to their self-efficacy, particularly STEM self-efficacy, persistence, and development of mentorship skills and behaviors. The findings of this study are important as they provide much-needed insight regarding the influence of e-mentoring training for women of color serving as mentors while enrolled in STEM degree programs. Given ongoing initiatives to support equitable participation of women and minorities in STEM and given the literature that supports the positive benefits of peer mentorship relationships in general, understanding the impact of mentor training and relationships on mentors specifically is needed. This study offers transferability in that others may find this research useful as they pursue work related to building self-efficacy and persistence in various contexts or with additional minority populations. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]