This study examined the nature and correlates of Mexican American mothers' and fathers' involvement in adolescents' peer relationships along 4 dimensions: support, restriction, knowledge, and time spent with adolescents and peers. Mexican American adolescents and their parents in 220 families described their family relationships, cultural orientations/values, and experiences with adolescents' peers in home interviews. In addition, time-use data were collected during a series of 7 phone calls to measure parents' time spent with adolescents and peers and parents' knowledge of adolescents' daily experiences with peers. Multilevel models revealed connections between parents' involvement in adolescents' peer relationships and both parents' Mexican and Anglo orientations and familism values and adolescents' peer experiences (e.g., deviant peer affiliations, friends' ethnic orientation). Findings further revealed some evidence that parent and adolescent gender moderated the patterns, with mothers' (but not fathers') restrictions on peer relationships being associated with adolescents' deviant peer affiliations and parents placing greater restrictions on daughters' than on sons' peer relationships when they had more frequent deviant peer affiliations. (Contains 1 footnote and 3 tables.)