In this article we discuss the traditional behavioral models of depression and some of the challenges analyzing a phenomenon with such complex and varied features. We present the traditional model and suggest that it does not capture the complexity of the phenomenon, nor do syndromal models of depression that dominate the mainstream conceptualization of depression. Instead, we emphasize ideographic analysis and present depression as a maladaptive dysregulation of an ultimately adaptive elicited emotional response. We emphasize environmental factors, specifically aversive control and private verbal events, in terms of relational frame theory, that may transform an adaptive response into a maladaptive disorder. We consider the role of negative thought processes and rumination, common and debilitating aspects of depression that have traditionally been neglected by behavior analysts.