Formal cancer support groups are assumed to assist women adapt to the physiological and psychosocial sequelae of breast cancer. To shed some light on this untested clinical assumption, this Roy Adaptation Model of Nursing-based study was designed to explore women's own reports about their adaptation to breast cancer and their participation in support groups. This article reports the results of the quantitative content analysis of structured telephone interviews with 70 women who participated in breast cancer support groups. Almost three-quarters of the women expressed a positive change in attitude toward breast cancer, and all regarded participation in the support groups as positive. A majority reported adaptive physiological, self-concept, role function, and interdependence mode effects of breast cancer and support group participation. Additional research is needed to show how different types of support groups contribute to women's responses. Research is also needed to separate the effects of support groups from other sources of social support that may have contributed to the women's responses, and to further explore feelings of normalization expressed by some women. Clinicians who conduct cancer support groups are encouraged to work with researchers to identify women's responses to the groups.