In meta-analysis format the effectiveness of Beck's cognitive therapy for depression was reviewed. Twenty-eight studies were identified that used a common outcome measure of depression, and comparisons of cognitive therapy with other therapeutic modalities were made. The results document a greater degree of change for cognitive therapy compared with a waiting list or no-treatment control, pharmacotherapy, behavior therapy, and other psychotherapies. The degree of change associated with cognitive therapy was not significantly related to the length of therapy or the proportion of women in the studies, and although it was related to the age of the clientele, a lack of adequate representativeness of various age groups renders these results equivocal. Implications for further outcome and process studies in cognitive therapy are discussed.