Previous research has established that family ethnic socialization messages promote ethnic-racial identity (ERI) development, yet it is unknown whether these effects remain constant throughout adolescence. The current study examined the time-varying effects of family ethnic socialization on ERI exploration and resolution among Latino adolescents (n = 323, M[subscript age at T1] = 15.31, SD[subscript age] = 0.76; 49.5% female). As adolescents progressed from middle to late adolescence, the relation between family ethnic socialization and exploration became stronger, while the relation between family ethnic socialization and resolution became weaker, with a significant difference between the magnitude of these associations emerging in late adolescence. The findings underscore the differential impact that family ethnic socialization messages can have on ERI developmental processes at different points in adolescence. In addition, the current study provides a useful illustration of how time-varying effects modeling can be used to examine how familial influences on youth development can change across developmental periods.