Meta-analytic methods were used to synthesize the results of published randomized, controlled-outcome studies of psychosocial interventions with adult cancer patients. Forty-five studies reporting 62 treatment-control comparisons were identified. Samples were predominantly White, female, and from the United States. Beneficial effect size ds were .24 for emotional adjustment measures, .19 for functional adjustment measures, .26 for measures of treatment- and disease-related symptoms, and .28 for compound and global measures. The effect size of .17 found for medical measures was not statistically significant for the few reporting studies. Effect sizes for treatment-control comparisons did not significantly differ among several categories of treatment: behavioral interventions, nonbehavioral counseling and therapy, informational and educational methods, organized social support provided by other patients, and other nonhospice interventions.