Efforts to broaden participation in science, technology, engineering, and mathematics (STEM) have remained at the forefront of initiatives across the United States (U.S.) and elsewhere. The importance of creating a STEM workforce that is reflective of the cultural, ethnic, and racial diversity of the overall population has been recognized. Peer mentoring has been demonstrated to be one effective method for encouraging and sustaining STEM participation. Studies have also demonstrated the importance of training peer mentors and mentees in best practices and arming them with the skillsets necessary for creating and maintaining effective peer mentoring relationships. This proceeding paper examines one such program, eSTEM, which was implemented across three historically Black institutions within the U.S. across two federally funded grant awards. In this proceeding: a) the structure of the virtual peer mentor and peer mentee training modules will be described, b) the overall outcomes of peer mentor and peer mentee training on undergraduate and graduate STEM students will be summarized, c) lessons learned from the implementation of the eSTEM program across multiple historically Black institutions will be shared, and d) future directions for refining, scaling, and providing public access to the peer mentor and peer mentee training resources will be discussed. [For the full proceedings, see ED656038.]