Background Mentorship models rarely seek generalizability across training programs at the graduate medical education (GME) level. Objective We examined the sustainability and effectiveness of an intervention to increase the number and usefulness of trainee mentorship. Methods A 0.20 full-time equivalent GME faculty adviser position (MD, MEd) implemented mentorship programs in residencies and fellowships. In group 1, 6 GME programs implemented the mentorship strategies prior to 2014, which were used to measure whether the number of mentor relationships were longitudinally sustained. In group 2, 10 different GME programs implemented the mentorship strategies in 2016, which were used to measure whether the intervention immediately increased the number of mentor relationships. To measure mentorship usefulness, trainees rated mentors' ability to promote clinical skills and personal and professional development. The remaining programs were the comparison. Responses from the 2014 and 2016 annual institutional trainee survey were analyzed. Results The incidence of group 1 reporting mentor relationships in 2014 compared to the incidence of group 1 in 2016 were 89% (41 of 46) and 95% (42 of 44), respectively, suggesting that the intervention was sustained for 2 years (P ¼ .26). Group 2 showed a higher proportion of trainees reporting mentors in 2016 (88%, 149 of 170) compared to preintervention (66%, 71 of 108; P ¼ .00001). Groups 1 and 2 reported significant increases in mentorship usefulness. Conclusions A GME initiative to enhance mentoring across specialties in 16 GME training programs was self-sustaining and effective. Address the common reasons for failed mentor relationships: forced relations, random assignment, and lack of trust. 2,12 & Provide intrinsic motivation for faculty to volunteer to the program. 4. Developing mentor profiles Volunteer mentor faculty develop profiles highlighting their personal and academic interests. Some programs hold in-person social engagements to introduce mentees to potential mentors. 13 Trainees use these profiles and engagements to identify shared interests and select mentors. 7 Goal & Avoid random assignment of mentors to mentees through voluntary participation and trainee selection of mentors. 5. Fostering mentor relationships Mentors meet with residents at least every 4 months. 2,7 A discussion guide is distributed outlining 6 areas of effective mentorship. 2 Each year, the program director reviews the mentor-mentee relationships and terminates relationships if necessary.