Individual differences shape the needs and characteristics of proteges, the processes through which mentoring may influence proteges' developmental trajectories, and the social networks into which the mentors enter. The literature on the influences of gender, ethnicity, and age on mentoring is reviewed and discussed as examples of how mentoring programs may have different influences on, and outcomes for, specific groups of youth. A focus on individual differences will help facilitate the development of mentoring programs that create a close fit between the needs of proteges and the services offered by the programs, as well as greater insight into what are the key elements of program effectiveness.