Objective: This study examined the environmental barriers and facilitators that hinder or promote participation among adults aging with physical disabilities. Method: Data come from an ongoing study of 1,331 individuals aging with long-term physical disability (M = 65 years). Linear regression examined the association between individual and socioenvironmental factors and participation restrictions in work, leisure, and social activities. Results: Pain, fatigue, and physical functional limitations were significant barriers to participation for individuals aging with physical disability. Barriers in the built environment also reduced participation, net of health and functioning. Poor access to buildings was especially problematic for participation among individuals not using any mobility aid to get around. But for those using wheel or walking aids, environmental barriers had no adverse effect on participation. Discussion: These findings highlight the importance of disentangling the role of different environmental factors by distinguishing between assistive technology for mobility and the physical built environment, including their interactive effects.