The cognitive model of depression postulates that the depressed individual's cognitions are not only negative, but erroneous and impervious to information from the environment. However, the valence of that information ultimately determines whether those cognitions are impervious or merely receptive. The actual life circumstances of the depressed individual, including social behavior, impoverished interpersonal relationships, and stressful life events, appear to be more negative than those of nondepressed people. These deficient and stressful life circumstances elicit negative reactions which depend at least as much upon the information being processed as upon the cognitive style of the processor. Beliefs and propositions of others provide an important source of information about the self and the world. Depressed people learn how to define the desirability and appropriateness of personal attributes and social situations from both their primary interaction group and the wider community. The depressed person and others then evaluate the degree to which the depressed person conforms to these social standards and situations. Thus, for the depressed individual, an on-going cycle between available information and cognition, mood, and behavior serves to maintain the depression. Cognitive therapy is particularly successful in treating depression since it alters behavioral deficits and negative cognitions. Finally, the problematic aspects of negative environmental information can be addressed through marital and family interventions and support groups. (BL)