Self-concept and social function following radical, modified radical or simple mastectomy for Stage I or II breast cancer, breast biopsy for benign breast disease, cholecystectomy or no operative procedure were measured across a fifteen-month period in a cross-sectional design and across a twelve-month period in a repeated measures design. Women selected for study were without other preexisting mental or physical illness. The degree of disability observed following mastectomy was considerably less than previously reported in uncontrolled studies, with the incidence of actual disturbance extremely small. Women receiving adjuvant therapies following mastectomy, but not women treated by mastectomy alone, reported significantly more body-image dissatisfaction and feminine selfimage concerns than the comparison groups. The findings refute previously published impressions of severe psychosocial maladjustments following mastectomy. The study suggests that post-mastectomy women vulnerable to poorer outcome would be those with lower expectations of good quality social support, other present life stressors, other pre-existing chronic diseases, and a disposition to believe in life outcomes as less under their own control.