Candidate: Dr. Kevin Fontaine, Assistant Professor of Medicine at Johns Hopkins University, who trained in Psychology at the Victoria University of Manchester, U.K., is seeking this Mentored Patient-Oriented Research Career Development Award (K23). In this revised application, he proposes a 3-year award period to complete advanced coursework and training in clinical trial design, biostatistics and research ethics, and to conduct a mentored research project to evaluate the effects of a new way to promote increased physical activity on patient oriented and disease outcomes in Rheumatoid Arthritis (RA). Project Rationale: RA is a chronic, systemic inflammatory disease that imposes a significant burden on the individual and the health care system. Although there have been advances in treating RA, it still compromises functional capacity and general health. Regular exercise improves function, disease activity, and general health in RA. Despite these benefits, most do not exercise. Thus, finding new ways to promote physical activity in patients with RA is important. Studies show that accumulating short bouts of moderate-intensity lifestyle physical activity (LPA) produces comparable health benefits to those obtained with conventional exercise. It is not known, however, whether LPA will produce benefits on functional capacity, disease activity, and general health in patients with RA. Design: The primary purpose of the mentored research proposed in this K23 application is to test the hypothesis that lifestyle physical activity (LPA) will produce benefits in patients with RA. To accomplish this, 104 adults with RA will be randomized to either a 16-week program of: 1) lifestyle physical activity (LPA); or 2) conventional exercise (CE). The primary outcome will be functional capacity. Secondary outcomes include disease activity, physical activity, fitness, and cardiovascular risk factors. The combination of education, training, and mentored clinical research in the supportive context of the Johns Hopkins University, one of the premier sites for mentored research in the country, will give Dr. Fontaine the skills and experience he needs to develop into an independent patient-oriented clinical researcher.