This chapter reviews how concepts of chronic depression have evolved in modern psychiatry. It describes the evaluation of patients who present with depressive symptoms that are 2 years or longer in duration. The chapter also reviews the evidence base for the management of these conditions, and presents an illustrative case. Chronic forms of depression were shown to be responsive to a variety of antidepressant medications, first in open-label and subsequently in a placebo-controlled trial. Half of the studies included patients with double depression and the remaining studies enrolled only patients with pure dysthymia. For patients who do remit or have a significant response to medication, psychotherapy, or combined treatment, the treating clinician is faced with the question of how to optimally treat the patient to maintain a robust and durable recovery. A significant body of work suggests that continuing the medication or psychotherapy are both effective relapse-prevention strategies.