This study compared three groups of substance abuse clients drawn from a representative sample of community treatment facilities in a large metropolitan area. Clients mandated to treatment from the criminal justice system (CJ-mandated; n = 124), clients currently involved with the criminal justice system but whose treatment was not legally mandated (CJ contact; n = 77), and clients who had no current criminal justice contact (no-CJ contact; n = 364) were compared with respect to sociodemographic and psychosocial characteristics including prior history of drug treatment and criminal justice system involvement, criminal behavior, psychological and physical health status, and treatment-related beliefs (e.g., motivation). The three groups differed from one another in certain respects; nonmandated clients currently in contact with the justice system showed similarities to other voluntary clients as well as to clients mandated to receive treatment. Implications for treatment are discussed.