Social stress, psychological distress, and psychosocial support effect the adjustment of breast cancer patients, influence their experience of and adherence to medical treatment, and may effect the course of the disease. The literature indicates that levels of distress, depression, and anxiety are substantially elevated among patients with breast cancer. These problems persist in a sizable minority of patients even years after diagnosis. Coping styles are related to adjustment and, in some studies, survival time. The nature of the relationship with physicians affects adjustment to the illness, satisfaction with treatment outcome, and adherence to medical treatment protocols, which can influence relapse and survival. In many but not all studies, serious life stress adversely affects medical outcome. Social support in general and structured psychotherapy in particular have been shown to positively affect both adjustment and survival time. Clear and open communication, expression of appropriate emotion, and collaborative planning and problem-solving enhance adjustment and improve outcome. Conversely, influences that isolate breast cancer patients from others or undermine support can have adverse medical and psychological consequences.