This study aimed to explore the role of school engagement and the mediation effect of acculturation in predicting 1.5 and second-generation migrant adolescents’ mental health and risk behaviors. Participants included 448 seventh to tenth grade Israeli students (mean age 14.50, 53% boys): 128 non-Jewish 1.5 generation migrant adolescents (children of migrants living in Israel), 118 second-generation migrants (children of migrants born and living in Israel), and an age-matched sample of 202 native-born Jewish adolescents. All participants completed a battery of questionnaires assessing mental health symptoms, engagement in risk behaviors, social adjustment, and school engagement. Both migrant adolescent groups also completed an acculturation questionnaire. Differences between groups in school engagement, mental health symptoms, and risk behavior were examined, and structural equation modeling (SEM) was used to investigate the hypothesized mediating effect of acculturation. Findings revealed substantially higher levels of mental health symptoms (p < .001) and risk behaviors (p = .001) among 1.5 and second-generation migrant adolescents compared with native-born adolescents, with no significant differences between 1.5 generation and second-generation migrants. Migrants’ age and gender were associated with mental health symptoms and risk behaviors—older participants engaged in more risk behaviors (p = .02), and females had elevated mental health symptoms (p = .007). Identification with the host country mediated the relationships between school engagement and mental health symptoms (ps .006 and .008) and risk behaviors (ps .001 and .004) in 1.5 generation and second-generation migrants, respectively. The results are discussed in reference to current theories and research, as well as practical implications for prevention and intervention.