Effective breast-conserving surgical techniques for early-stage disease were developed to improve breast cancer patients' quality of life. The literature comparing the psychosocial sequelae of these newer treatments with mastectomy is ambiguous and shows an unexpected lack of substantial benefits. To clarify these inconsistencies, meta-analytic methods were used to summarize the findings of 40 investigations. Mean weighted effect sizes were calculated for 6 psychosocial outcomes. Modest advantages for breast-conserving surgery were identified for psychological, marital-sexual, and social adjustment; body/self-image; and cancer-related fears and concerns. Method of assignment to treatment and timing of assessment were relevant for some outcomes.