Research mentor training (RMT), based on the published "Entering Mentoring" curricula series, has been shown to improve the knowledge and skills of research mentors across career stages, as self-reported by both the mentors engaged in training and their mentees. To promote widespread dissemination and empower others to implement this evidence-based training at their home institutions, we developed an extensive, interactive, multifaceted train-the-trainer workshop. The specific goals of these workshops are to 1) increase facilitator knowledge of an RMT curriculum, 2) increase facilitator confidence in implementing the curriculum, 3) provide a safe environment to practice facilitation of curricular activities, and 4) review implementation strategies and evaluation tools. Data indicate that our approach results in high satisfaction and significant confidence gains among attendees. Of the 195 diverse attendees trained in our workshops since Fall 2010, 44% report implementation at 39 different institutions, collectively training more than 500 mentors. Further, mentors who participated in the RMT sessions led by our trained facilitators report high facilitator effectiveness in guiding discussion. Implications and challenges to building the national capacity needed for improved research mentoring relationships are discussed.