Objective The aim of this study was to examine the relationships between pathological narcissism (narcissistic grandiosity and narcissistic vulnerability), dysfunctional attitudes (perfectionism and dependency on other people), and depressive symptoms in psychiatric outpatients. Method A sample of 234 adult psychiatric outpatients (57.3% male; mean age 44.39 years) completed the Pathological Narcissism Inventory, the Dysfunctional Attitudes Scale–Form A, and the Depression, Anxiety, Stress Scales–21. Results Narcissistic vulnerability exhibited unique positive correlations with depressive symptoms, whereas narcissistic grandiosity showed substantially weaker correlations with depressive symptoms. Perfectionism partially mediated the relationship between narcissistic vulnerability and depressive symptoms. The mediating role of dependency was not confirmed. Conclusions Among adult psychiatric outpatients, narcissistic vulnerability is more strongly related to depressive symptoms than narcissistic grandiosity, and dysfunctional perfectionism represents one of the underlying mechanisms of this relationship. The implications of these findings are discussed in relation to the Diagnostic and Statistical Manual of Mental Disorders diagnostic criteria and the treatment of pathological narcissism.