This study examined predictors of physical and psychological integration in homeless adults with problematic substance use. Homeless adults with problematic substance use (n = 115) in Ottawa, Canada, completed questionnaires regarding their demographics (age, gender, Aboriginal ethnicity), health and social functioning (physical health, mental health, alcohol use problems, drug use problems, social skills), environmental factors (satisfaction with personal safety, social support), physical integration, and psychological integration. Participants reported low physical integration (i.e., participation in activities in the community) and did not feel strongly psychologically integrated (i.e., sense of belonging). The final models accounted for 36% and 19% of the variance in physical and psychological integration, respectively. Higher levels of social skills and social support were associated with greater physical integration. Higher levels of mental health functioning and satisfaction with safety were related to greater psychological integration. Implications of the findings for community support services are discussed.