Depression is remarkably persistent and recurrent. Why? Although several predictors of depression chronicity have been identified, a conceptual framework regarding mechanisms whereby depression chronicity occurs is lacking. The goal of this article is to explain depression chronicity, at least in part, with reference to processes, mostly interpersonal in nature, that serve to extend and reestablish depression. Several such processes are described, and available empirical evidence regarding each is reviewed. Clinical and research implications of the present conceptualization are elucidated. To the degree that these processes receive continued empirical support as mechanisms whereby depression persists, they represent leverage points to combat the vexing problem of depression chronicity.