The role of gender in shaping the course and quality of adult-youth mentoring relationships was examined. The study drew on data from a large, random assignment evaluation of Big Brothers Big Sisters of America (BBSA) programs [Grossman, J. B., & Tierney, J. P. (1998). Does mentoring work? An impact study of the Big Brothers Big Sisters program. "Evaluation Review," 22, 403-426], and focused on variables associated with youth's relationships with their parents and mentors. At baseline, girls reported significantly lower levels of parental trust and higher levels of alienation from their parents than boys. Nonetheless, girls' mentoring relationships lasted significantly longer than those of boys. Moreover, girls were less satisfied than boys in short- and medium-term relationships, but were more satisfied than boys in long-term relationships. Similarly, girls in long-term relationships rated mentoring as more helpful than either the boys or the girls in the shorter-term relationship groups. Particularly in light of the heightened mistrust and alienation from parents at baseline, and the role of improved parent relationships in mediating the effects of mentoring, the protective aspect of longer-lasting mentoring relationships may be particularly salient for girls.