Formal mentoring programs are becoming more popular as organizations attempt to reap the benefits that have long been associated with informal mentoring. The present study adds to the small number of mentor-centric studies and offers a unique longitudinal examination of formal mentoring programs. Findings suggest that as formal mentoring relationships develop over time, mentors begin to use their time more efficiently and the negative effects of cross-gender differences dissipate. Furthermore, whereas mentor reports of psychosocial support and role modeling appear to relate to mentor program satisfaction and protégé reports of mentor effectiveness, reports of vocational support appear to have no impact on these variables. Study limitations are discussed, and implications for future research and for practice are suggested.