Research on the thought processes of substance abusers indicates that they are plagued with dysfunctional thinking patterns that precede the use of mood-altering substances. The dysfunctional thinking is characterized by rigidity and excess where one is either first or last, best or worst. This can contribute to substance abuse by mandating an excess that can lead to addiction and by fostering an overreaction to life's cruelties that can encourage drinking for 'pain control.' An intensive treatment program using cognitive theory and techniques can be a powerful change mechanism. Under such a mechanism, the client is taught the skills of testing and examining underlying assumptions and beliefs to foster responsibility for one's own thoughts and behavior. Cognitive therapy should also be applied in prevention efforts, ideally beginning during the school years. Prevention should teach persons to cope constructively with life's cruelties and deemphasize educational competition and perfectionism. 16 references.