The numerous physical and psychological benefits of physical activity have been well documented. However, the proportion of adults with disabilities who participate in regular health-related physical activities is far less than the number of their age-range peers without disabilities (Healthy People, 2010). A goal of Healthy People 2010 is to identify ways to increase physical activity participation among the posited populace. The social minority model recognizes certain psychosocial factors that may decrease motivation toward physical activity (Kosma et al., 2002). Given the limited theory-driven empirical evidence toward the identification of motivational strategies, the purpose of this cross-sectional, nationwide study was to explore the most influential factors in physical activity based on the transtheoretical model (Prochaska & DiClemente, 1983). Survey questionnaires were mailed to a volunteer sample of 411 adults with physical disabilities. From the 334 individuals (response rate=81.27%) who responded to the survey, 322 participants (females=62.1%, males=37.3%; mean age=52.5, age range=17-89) qualified to remain in the study. The most prevalent disability categories were post-polio (17.7%), multiple sclerosis (11.8%), and spinal cord injury (10.9%). The study participants completed standardized self-report measures of exercise stages of change (i.e., physical activity intention and behavior), processes of change (i.e., strategies to increase physical activity), self-efficacy (i.e., perceived self-confidence), decisional balance (i.e., perceived pros and cons), and barriers toward exercise. Predictive discriminant function analyses revealed that the behavioral processes of change (r=.662; rē=.44), self-efficacy (r=.662; rē=.44), and decisional balance (r=.537; rē=.29) were the most important predictors in classifying the participants within the proposed stages of change. The most stable stages in classification accuracy were the maintenance (89%-89.6%), precontemplation (68.9%-70.5%), and contemplation (51.7%-55.2%), whereas the least stable stage was preparation (0%-23.8%). The results of this study provide valuable information for practitioners, scholars, and health promoters regarding the most important factors in which intervention programs can focus on for positive behavior change. Exercise stages of change represent the behavioral and cognitive characteristics regarding physical activity participation. Therefore, valid and reliable classification across the stages is an essential preface of a stage-matched motivational program to influence physical activity initiation, enhancement, and adherence. Thus, validity issues of the proposed stages-of-change scale are considered. Funding for this project was provided by the National Institute on Disability and Rehabilitation Research, U.S. Department of Education (CFDA No. 84.133b-9).