For the majority of individuals suffering from depression, any given episode is likely to remit without intervention, but subsequent episodes are apt to occur in the future (Zis & Goodwin, 1979). Given this high rate of renewed subsequent symptomaticity, increased attention has been paid in recent years to the distinction between blocking relapse, the return of symptoms associated with a prior episode, versus the prevention of recurrence, the onset of a wholly new episode (Post, 1959; Prien, 1984; Prien & Caffey, 1977; Prien & Kupfer, 1986; Quitkin, Rifkin, & Klein, 1976). In this chapter we focus on the issue of the long-term stability of treatment gains. We do so with particular reference to a recently completed comparative trial contrasting cognitive therapy and imipramine tricyclic pharmacotherapy, each alone and in combination, in the treatment of depressed outpatients (Hollon, DeRubeis, Evans, Wierner, Garvey, Grove, & Tuason, 1990). In addition to contrasting the efficacy of each intervention with respect to the reduction of acute symptomatology, we also evaluated the long-term efficacy of each over a two-year posttreatment follow-up period (Evans, Holton, DeRubeis, Piasecki, Grove, Garvey, & Tuason, 1990). As we shall see, our initial goal was to evaluate the impact of the different interventions on the prevention of subsequent episodes (recurrence). While differential effects were found (Evans et al., 1990), it is not clear that these findings were so much informative about recurrence as about clinical relapse.