In this study, we explored the effects of mentor and mentee insecure attachment dispositions (ambivalence and avoidance) on mentoring relationship quality while considering the specific nature of the interactive mentoring context. Participants (N = 252 matches) were enrolled in the MIRES program, a one-year college-based mentoring program that matches late adolescent mentees (17-year-olds) with young adult mentors (23-year-olds), designed to facilitate the transition to college. Using data drawn from mentors’ logbooks (at nine time points), two interactive contexts were addressed: (1) situations involving mentee academic issues and mentor proactive academic support (academically oriented), and (2) situations involving mentee personal issues and mentor emotional support, and caring (emotionally oriented). Linear regression results showed that both mentors’ and mentees’ avoidance uniquely predicted lower reports of mentoring relationship quality, but especially in emotionally oriented matches and when their partners’ attachment ambivalence was high. In matches less focused on emotional support, mentors’ attachment avoidance interacted with mentees’ ambivalence to predict positive mentoring relationship quality. Theoretical, practical, and mentor training issues are discussed.