Assertive mental health outreach to persons who are homeless, which operates under the premise that mental illness must be understood and treated within the individual's social and economic environment, points towards the goals of community membership and 'citizenship'--a connection to the rights, responsibilities, roles, and resources that society offers through public and social institutions and informal 'associational life'--for homeless persons. The authors argue that the concept of citizenship is a useful framework for approaching these goals. The authors review the principles of assertive mental health outreach and relevant aspects of contemporary citizenship theory; present a case example of outreach leading to a 'citizenship project'; and discuss the potential benefits and pitfalls of a citizenship framework, including strategies and recommendations for program administrators, researchers and policy makers. (Authors)