People with mobility disabilities are at greater risk than the general population for incurring health problems. Many of these conditions are preventable through behavior and lifestyle changes such as exercise and physical activity. Recent evidence suggests that people with disabilities experience the same physiologic response to exercise as the general population. Nonetheless, nearly three-fourths of those with disabilities report being entirely sedentary or not active enough to achieve health benefits. Despite some knowledge of issues that limit physical activity among this population, few studies have investigated methods for promoting physical activity adoption among people with disabilities, including wheelchair users. The purpose of this study is to test the effectiveness of a behavioral intervention to promote physical activity adoption over 6 months and maintenance of physical activity over another 6 months by community-dwelling manual wheelchair users.