The Women's Intervention Nutrition Study (WINS) is an ongoing randomized multicenter clinical trial testing the hypothesis that dietary fat intake reduction as an adjuvant to standard breast cancer therapy will reduce disease recurrence and increase survival for women with localized breast cancer. The hypothesis is based on preclinical studies, epidemiological observations and plausible mediating mechanisms of action. Currently, 2096 women (on target to meet the 2,500 final accrual objective) have been randomized within one year of diagnosis to a fat intake reduction Intervention or a Control group. The dietary intervention, based on social cognitive theory, involves individualized counseling by nutritionists trained in motivational interviewing and includes goal assessment, tailored messages, self-monitoring and cognitive restructuring. Dietary adherence, assessed with serial, unannounced telephone recalls has been maintained through three years with demonstrated significant (P<0.0008) reduction in dietary fat intake in intervention participants. Thus, WINS has a demonstrated capability to both accrue the required population of breast cancer patients and maintain sufficient dietary adherence in the Intervention group to fully address the study hypotheses. Patients continue to be followed for disease-free survival (as primary study endpoint) and overall survival. Developed long-term adherence strategies contain a Motivational Action Plan (MAP) that includes an individualized assessment of needs with booster sessions. Centralized retention protocols including "partnering" with participants, and newsletters are fully operational. Study organization includes an Administrative Unit, an External Advisory Committee, a Nutrition Coordinating Unit, a Clinical Director's Office, a Statistical Coordinating Unit, two Regional Nutrition Centers and over thirty-four Clinical Sites, and incorporates established quality assurance 'procedures. Completion of this study will provide definitive evaluation of the effect of dietary fat intake on breast cancer patient outcome. This proposal requests support needed to continue the active dietary intervention clinical follow-up and endpoint determinations needed to fully assess all study hypotheses.