This review of the literature on peer and cross-age tutoring emphasizes programs in mathematics and suggests that such programs have positive academic outcomes for African American and other minority students as well as for White students who participate as tutors, as tutees, or both. Such programs also appear to have a positive impact on a variety of attitudinal and socioemotional outcomes, such as students' attitudes towards school, their self-concepts, and their sense of academic efficacy. This review also explores whether specific features of the tutoring programs (e.g., tutor training and amount of tutoring) or characteristics of the students (e.g., academic level prior to tutoring and gender composition of tutor-tutee pairs) affect various outcomes. Role theory is used as a theoretical framework to explain some intriguing and surprising findings (e.g., why tutors show academic gains even when they do not receive additional subject matter instruction, why longer and/or more substantial tutoring programs may not foster greater immediate academic gains than shorter programs, and why mixed-sex pairs do not consistently reap benefits equal to those of same-sex pairs). Finally, implications of the review for the development of peer and cross-age tutoring programs are discussed.