1. Convulsive photoshock is an effective treatment procedure.2. The convulsive seizure, whether produced by electric or photo-chemical means, has therapeutic value in the treatment of affective psychosis.3. Periods of induced paroxysmal brain wave activity alone ( subconvulsive treatment) without subsequent convulsion resulted in no improvement beyond that produced by the psychotherapeutic effect of routine hospital care.4. The amount of postshock confusion is not related to recovery and clouds the picture when immediate evaluation of treatment is desired. Postshock confusion was less frequently noted after photoshock than after an equal number of electroshock treatments.5. Fear of treatment did not play a role in producing remission from psychotic symptoms.6. Evidence is discussed suggesting that convulsions produced by different means may have different modes of action in the central nervous system thus accounting for differences in recovery rate, degree of alteration of convulsive threshold, and amount of mental confusion.