Latino youth can experience a range of cultural (i.e., ethnic discrimination and acculturative stress) and familial (i.e. family conflict) risk factors that can contribute to their perceived stress, thereby increasing their risk for depressive symptoms and cigarette smoking. To understand the mechanisms by which ethnic discrimination, acculturative stress and family conflict influence the risk for depressive symptoms and cigarette smoking of youth, the current study investigated the mediating role of perceived stress in these associations. The data came from a longitudinal study of acculturation and substance use with 1919 Latino adolescents (52% female; 84% 14 year-olds; 87% U.S. born). Structural equation modeling indicated that discrimination and family conflict (Time 1) related with higher perceived stress (Time 2), which, in turn, related with more depressive symptoms and smoking (Time 3). The results suggest that perceived stress might be one mechanism by which ethnic discrimination and family conflict contribute to Latino youth symptoms of depression and cigarette smoking. The findings highlight the need for prevention and intervention strategies that help youth manage their general perceived stress and/or focus on stress reduction techniques.