Response-contingent electric shock was evaluated in a laboratory and criterion situation before using it to eliminate infrequent and unpredictable biting and destructive acts from the repertoire of a retarded adolescent. Although the initial results were dramatic, the effects of shock were highly discriminated and the therapeutic objectives were not accomplished. The study demonstrates the power and some limitations of shock punishment and is presented so that others will be better prepared for problems that may arise before the goals of a program involving shock punishment will be realized.