While formal curriculum on resident teaching have been associated with improved career growth and sustained positive impact on patient care, mentorship skills are rarely taught in academic medicine. We hypothesized that a formalized resident mentorship curriculum coupled with a near-peer resident-medical student mentoring program would improve resident career growth. A multi-institutional, prospective, phase 2 intervention study, approved by each participating center's institutional review board, was conducted from 4/2022-10/2022 among interested residents in the Radiation Oncology Education Collaborative Study Group Graduate Medical Education. Intervention included: 1) a 4-week mentorship curriculum (utilizing a Six Steps approach) composed of self-guided readings, didactic lecture, and 30-minute faculty check-in, and 2) a formalized 1:1 resident-medical student mentorship program during an existing radiation oncology sub-internship with weekly meetings. Resident participants completed the Mentorship Competency Assessment (MCA), a 26-item validated survey on mentorship skills in medicine scored from 0 (most unprepared) to 7 (most prepared) before and after the intervention. The primary endpoint was average change in MCA skill from pre- to post-intervention survey, with score ranges from -7 (a decrease in 7 points) to +7 (an increase of 7 points). A total of 8 residents participated and all completed pre- and post-intervention surveys. Most residents were PGY-4/5 (75%), from programs with >10 residents (68%), and did not have prior training in teaching (88%) or mentorship (88%). Residents met students on average twice weekly (range 1-3) for an average of 2 hours a week (range 1-5). After the program, most residents felt confident in being a future mentor to students (100%), their overall well-being was positively impacted (63%), and their mentorship relationships were positively impacted (50%). All 26 mentorship skills increased on MCA after intervention (average +1.3/7 per skill). Skills that showed greatest improvement were helping mentees network effectively (+2.6/7), acquire resources (+2.1/7), negotiate a path to professional independence (+2.0/7), set career goals (+1.8/7), and balance work and personal life (+1.7/7). Skills that showed least improvement were establishing a relationship based on trust (+0.4/7), identifying and accommodating different communication styles (+0.6/7), providing constructive feedback (+0.7/7), and aligning mentor-mentee expectations (+0.8/7). The formalized mentorship program improved mentorship skills among residents, translating to increased satisfaction in residents' own mentorship relations and overall well-being. Further studies are needed to assess the sustainability of these skills, as well as impact on career growth and satisfaction.