Three theoretical viewpoints have dominated the recent empirically oriented literature on depression: Beck's cognitive view, Seligman's helplessness model, and Lewinsohn's theory implicating a low rate of response-contingent reinforcement. In this paper, each theory is evaluated individually in terms of its empirical support and adequacy as a theory, and the theories are contrasted and compared with one another. Special attention is given to recent studies not discussed in the theorists' major summary papers and to empirical findings whose relevance to a particular theory has not previously been noted. Although there is reason to believe that any or all of the elements suggested by the three theorists-perception, control, and rate of reinforcement-are of import in depression, none has been proven to be a necessary antecedent of depressive episodes.Conversations with William Batsel have contributed greatly to this article. In addition, Carol