This meta-analytic study examined the relationship among the constructs of acculturation, enculturation, and acculturation strategies (i.e., integration, assimilation, separation, marginalization), and mental health. Data from 325 studies (163 journal articles and 162 dissertation studies) were analyzed using a random-effects model, across a broad spectrum of negative mental health (NM: depression, anxiety, psychological distress, and negative affect) and positive mental health (PM: self-esteem, satisfaction with life, and positive affect). Overall, acculturation was favorably associated with both NM (negatively) and PM (positively), whereas enculturation was favorably related only to PM (positively). In fact, enculturation was positively related to anxiety. The specifics of these relations were further examined using the following moderators: (a) researchers' operationalization of acculturation/enculturation (i.e., linearity, dimensionality); (b) contextual influences (i.e., when and where the study was conducted); and (c) sample characteristics (i.e., voluntariness of residency, race, gender, age). Overall, bilinear measures of acculturation indicated a positive association with PM, while unilinear measures did not. External acculturation (e.g., language, behaviors) and internal enculturation (e.g., identity) were most favorably related to mental health. The place of study had differential effects on the relation of enculturation and NM. Acculturation appeared to be especially important to Asian Americans, whereas enculturation was to African Americans. Differential effects of age suggested the need to consider life-span development of needs and social roles in relation to acculturation and enculturation. Both correlational analyses and mean comparisons affirmed that integration was the most favorable acculturation strategy to mental health. Implications for research, practice, and theory are discussed. (Contains 5 tables and 1 figure.)