Cognitive Therapy and Research, Vol. 25, No. 2, 2001, pp. 117–135 Predicting Symptom Return from Rate of Symptom Reduction in Cognitive–Behavior Therapy for Depression Darcy A. Santor 1,3 and Zindel V. Segal 2 Numerous studies have examined rates of symptom reduction and symptom return across treatment modalities; however, few studies have investigated the degree to which rate of symptom reduction during treatment is related to symptom return following treatment. We examined the relation between symptom return 3 and 6 months after completing treatment and several measures of symptom reduction during treatment, including amount of symptom reduction early in treatment, rates of symp- tom reduction over different phases of treatment, as well as the number of weeks in which individuals were asymptomatic. Rate of symptom reduction in the first 10 weeks of treatment was a stronger predictor of symptom return at 3 and 6 months after treatment than (a) pretreatment depressive severity, (b) symptom reduction after the first two sessions of treatment, (c) symptom reduction over all 20 weeks of treatment, and (d) number of weeks in which individuals were asymptomatic. Results also showed that severity of depressive thoughts at pretreatment was one of the only predictors of rate of symptom reduction during treatment and that estimating rates of symptom reduction simply by summing weekly BDI scores was as efficient at predicting symptom return as estimating rate of symptom reduction with more com- plex hierarchical linear regression models. Results of this research provide researchers and clinicians with new ways of measuring symptom reduction as well as the means of identifying individuals, before treatment has ended, who are likely to experience symptom return. KEY WORDS: depression; cognitive therapy; symptoms; relapse; resilience. INTRODUCTION Relapse following the effective treatment of depression constitutes one of the most important issues to emerge recently in depression research (Belsher & Cos- 1 Department of Psychology, Dalhousie University, Halifax, Nova Scotia, Canada. 2 Cognitive Behavioural Therapy Unit, Clarke Institute of Psychiatry, and Department of Psychology, University of Toronto, Toronto, Ontario, Canada. 3 Correspondence should be directed to Darcy A. Santor, Department of Psychology, Dalhousie Univer- sity, Halifax, Nova Scotia, Canada B3H 4J1; e-mail: dsantor@is.dal.ca. 117 0147-5916/01/0400-0117$19.50/0  2001 Plenum Publishing Corporation