Background: Challenges of migration, particularly concerning the process of acculturation are associated with an increased risk of mental illness. Vietnamese migrants constitute the largest Southeast Asian migrant group in Germany, yet there is no data on the relationship between the mental health status and acculturation among this population. Aims: Therefore, the present study examines the relationship between two well-established dimensions of acculturation, that is, dominant society immersion (DSI) and ethnic society immersion (ESI), the four resulting acculturation strategies (integration, assimilation, separation and marginalization), and severity of depression. Methods: A sample of N = 113 first-generation Vietnamese outpatients from a psychiatric outpatient clinic for Vietnamese migrants in Germany was studied regarding their self-reported depressive symptoms (Beck Depression Inventory-II (BDI-II)) and acculturation (Stephenson Multigroup Acculturation Scale (SMAS))....