The purpose of this book was to evaluate the effectiveness of Group Cognitive-Behavioural Therapy among Iranian migrants with Major Depressive Disorder in Austria. Twenty-three Iranian women and men with an average, 40.4 years old that met DSM-IV criteria for MDD were recruited by the snowball sampling. Nine of them were randomized to the GCBT, six to the individual CBT, and eight to the Waiting-List control groups. Depressive symptoms, intensity of depression and the types and severity of Automatic Thoughts were assessed by BSI (Scale 4), the BDI-II and the ATQ respectively. Suicidal ideation and Generalized Anxiety Disorder were distinguished and excluded by the BSSI and DASS-21. The findings from this study suggest that the reasons behind the Iranian migrant´s depression may be related to their chosen dysfunctional acculturation strategies. Therefore, GCBT can be considered an appropriate treatment for Iranian migrants with MDD due to its consistent relation with the Iranian socio-cultural background, which can encourage the Iranian migrants to modify their acculturation attitudes.