In recent years, depression has been reconceptualized from a short, self-limiting condition to longer time frames as a result of the observation that most depressed persons will have a recurrent or chronic course. Similarly, antidepressant therapy, either with drugs or psychotherapy, has been recast in longer time periods. The best current evidence indicates that ongoing treatment with medications and certain types of psychotherapy (with interpersonal psychotherapy [IPT] and cognitive behavioral psychotherapy [CBT] and related approaches being the most widely tested) reduce risk for relapse (defined as the return of the original episode of depression) and recurrence (the occurrence of a new episode). IPT, CBT, and medications reduce risk while they are continued, but only CBT seems to have an enduring effect after it is discontinued. Significantly, combining CBT with antidepressant medications initially may reduce the preventive effect of CBT on relapse and recurrence. Therefore, the choice of initial treatment determines the need for longer-term continuation of therapy.