Although everyone experiences transient feelings of depression and unhappiness, the experience may be characterized as a depressive disorder when these feelings begin to dominate everyday life and cause emotional and functional impairment. According to the Diagnostic and Statistical Manual of Mental Disorders (Diagnostic and Statistical Manual [DSM-IV]; American Psychiatric Association [APA] 2000), the two main categories of depressive disorders include major depressive disorder (MDD) and dysthymic disorder (DD). Both disorders are defi ned by a similar pattern of symptoms, which may include depressed mood, anhedonia, sleep and appetite disturbances, fatigue or low energy, feelings of worthlessness, guilt, and/or suicidal ideation. While MDD lasts at least two weeks and is usually associated with moderate to severe symptoms, DD represents a more persistent and low-grade depression that lasts two years or longer. Major depression and dysthymia frequently co-occur (known as double depression), and depressive disorders, in general, tend to exhibit high rates of comorbidity with other Axis I and Axis II conditions, particularly anxiety disorders (Brown et al. 2001; Mineka, Watson, & Clark 1998).