Total knee replacement (TKR) utilization continues to increase, placing substantial burden on the economy. As patients live longer with TKR, it is essential to identify strategies that will maximize long-term functional outcomes and promote health-related quality of life and independence as adults age after surgery. The majority of TKR patients meet criteria for overweight/obesity and remain physically inactive after surgery, both of which heighten the risk of poor functional outcomes and disability. Further, most patients will actually gain weight within two years after surgery. Patients after TKR are also at an increased risk of death from cardiovascular and mental diseases. Promoting weight management may be an effective strategy to improve long-term functional and physical activity outcomes after TKR, reduce the risk of disability and death from cardiovascular and mental diseases, and improve the value of the costly surgery. We propose to examine the effectiveness of a Patient-Centered (PACE) weight loss program in adults after TKR in a fully-powered, two-arm randomized controlled trial. Patients (n=250) will be randomized to receive either (1) PACE weight loss program or (2) Chronic Disease Self-Management (CDSM) control group. PACE participants will start the patient-centered program 12 weeks after TKR and continue for 12 months. PACE is tailored to the patients’ needs and unique barriers to diet and physical activity. PACE focuses on reducing caloric intake and increasing physical activity (aerobic and resistance) to facilitate a weight loss of at least 7% of initial body weight. Coaching calls with a trained behavioral interventionist will occur weekly during months 1-4, biweekly during months 5-6, and monthly during months 7-12. No coaching will occur during the maintenance phase (months 13-18). CDSM will receive a self-directed version of the program and monthly calls on topics not related to study outcomes. Data collection will occur at baseline (12 weeks after surgery), 6 months (end of intensive intervention), 12 months (end of treatment), and 18 months (maintenance). Assessments will include measures of weight, secondary outcomes (e.g., physical activity, pain, function), and potential mediators from our conceptual model (e.g., adherence, self-efficacy, autonomy, competence). Data related to the cost of implementing the PACE weight loss intervention relative to Control will also be collected to examine the cost-effectiveness of reducing weight on patient outcomes. The primary outcome is weight change at 6 months. The expected outcome from this study is to determine the effectiveness and long-term maintenance of a refined patient-centered weight loss program tailored specifically for adults after TKR. If PACE is effective at improving short- and long-term outcomes, and is found to be cost-effective, orthopedic centers and/or insurance companies could consider offering this program to TKR patients, offering significant benefits to t...