This article reviews the empirical evidence of impaired social skills associated with depression. Conceptualizations of social skills are examined followed by evidence from self-report, observer-rating, and behavioral assessments of depressed people's social skills. Evidence of social skills deficits in children with depression and in people with bipolar disorder is also examined. The effectiveness of social skills training as a treatment of depression is evaluated. Three different theoretical relationships between disrupted social skills and depression are described and evaluated, including poor social skills as a cause of depression, depression as a cause of poor social skills, and poor social skills as a vulnerability factor in the development of depression. Currently, there is some evidence to support each of these conceptualizations, as the relationship between poor social skills and depression can take a variety of forms.