There is now considerable evidence showing that culture shapes psychological processes, and this extends to depression and psychopathology more generally. In particular, an understanding of the processes and mechanisms through which culture influences depression is important not only to clinical practice, but also in the designing of interventions to promote resilience to depression. For example, such cultural understanding helps therapists to determine whether and when clients will be influenced by culture and its norms, and accordingly, the impact on their expression, assessment, diagnosis, and treatment of depression. The present thesis adopts a social identity perspective to advance research on the cultural underpinnings of depression in three research streams that investigate (a) the symptomatic presentation of depression, (b) cultural factors associated with vulnerability, and (c) resilience, to depression.Much of the work on the relationship between culture and the expression of depression has centered on Asians" tendency to emphasize somatic symptoms of the condition over psychological symptoms. However, despite extensive investigation of Asian somatization, there has been little progress in explaining how and when culture affects depression expression. To address this gap, the studies in Chapter 2 drew on social identity principles and processes to explain when culture and its norms would affect somatization.Three studies were conducted to investigate the role of cultural identity on somatization; predicting that norm endorsement would occur only when individuals identified with their culture. The key finding was that among Asians, normative expectations of collectivism predicted somatization, but only when participants strongly identified with Asian culture.These findings highlight the centrality of identification processes to cultural influence on depression.Investigations of culture and depression expression tend to conceptualize the Western perspective as the frame of reference or norm. That is, Asian somatization is commonly viewed as dysfunctional in Western contexts, whereby Asians and their emphasis on somaticizing depression is often portrayed as "that which needs to be explained". In Chapters 3 and 4, we shifted focus to studying the effect of Western culture on depression, an arguably neglected area of research. More importantly still, the socially potent nature of cultural norms in exerting influence tends to be overlooked in the literature of this field. Hence, the studies in these chapters drew on a norm-based approach to characterize cultural influence, and investigated the effects of specific collective-level cultural factors (i.e., social norms) associated with vulnerability to depression among Westerners.iii Along these lines, the study reported in Chapter 3 examined whether and why social norms communicating the value of happiness (that happiness is desirable) could potentially make individuals feel worse (i.e., more depressed). We also investigated differences in these effect...