BACKGROUND Few studies to date have used the cancer diagnosis as a teachable moment to promote healthy behavior changes in survivors of cancer and their family members. Given the role of obesity in the primary and tertiary prevention of breast cancer, the authors explored the feasibility of a mother-daughter weight loss intervention. METHODS A randomized controlled trial of a mailed weight loss intervention was undertaken among 68 mother-daughter dyads (n = 136), each comprised of a survivor of breast cancer (AJCC stage 0-III) and her adult biological daughter. All women had body mass indices ≥ 25 kg/m2 and underwent in-person assessments at baseline, 6 months, and 12 months, with accelerometry and exercise capacity performed on a subset of individuals. All women received a personalized workbook and 6 newsletters over a 1-year period that promoted weight loss; exercise; and a nutrient-rich, low-energy density diet. A total of 25 dyads received individually tailored instruction (INDIVIDUAL), 25 dyads received team-tailored instruction (TEAM), and 18 dyads received standardized brochures (CONTROL). RESULTS The trial met its accrual target, experienced 90% retention, and caused no serious adverse events. Significant differences in baseline to 12-month changes were observed between INDIVIDUAL versus CONTROL mothers for body mass index, weight, and waist circumference (WC); significant differences also were observed in the WC of corresponding daughters (P < .05). Significant differences were found between INDIVIDUAL versus CONTROL and TEAM versus CONTROL dyads for WC (P = .0002 and.018, respectively), minutes per week of physical activity (P = .031 and.036, respectively), and exercise capacity (P = .047 for both). CONCLUSIONS Significant improvements in lifestyle behaviors and health outcomes are possible with tailored print interventions directed toward survivors of cancer and their family members. For greater impact, more research is needed to expand this work beyond the mother-daughter dyad. © 2014 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.