To determine the efficacy of an Internet-based Arthritis Self-Management Program (ASMP) as a resource for arthritis patients unable or unwilling to attend small-group ASMPs, which have proven effective in changing health-related behaviors and improving health status measures. Randomized intervention participants were compared with usual care controls at 6 months and 1 year using repeated-measures analyses of variance. Patients with rheumatoid arthritis, osteoarthritis, or fibromyalgia and Internet and e-mail access (n = 855) were randomized to an intervention (n = 433) or usual care control (n = 422) group. Measures included 6 health status variables (pain, fatigue, activity limitation, health distress, disability, and self-reported global health), 4 health behaviors (aerobic exercise, stretching and strengthening exercise, practice of stress management, and communication with physicians), 5 utilization variables (physician visits, emergency room visits, chiropractic visits, physical therapist visits, and nights in hospital), and self-efficacy. At 1 year, the intervention group significantly improved in 4 of 6 health status measures and self-efficacy. No significant differences in health behaviors or health care utilization were found. The Internet-based ASMP proved effective in improving health status measures at 1 year and is a viable alternative to the small-group ASMP.