Problem: Greater awareness of the role of parental substance abuse in child maltreatment makes it imperative that the substance abuse treatment and child welfare systems coordinate services for these parents. Yet little is known about the characteristics of child-welfare involved parents (primarily mothers) who enter into substance abuse treatment. This paper compares the characteristics of mothers in substance abuse treatment who were and were not involved with child welfare services, and discusses the treatment implications of these differences. Method: Data were obtained from a statewide treatment outcome monitoring project in California. Clients were assessed at treatment admission using the Addiction Severity Index. Bivariate analyses and multivariate logistic regression were conducted comparing mothers who were (N=1,939) and were not (N=2,217) involved with child welfare. Results: Mothers who were involved with child welfare were younger, had more children, and had more economic problems. They were more likely to be referred by the criminal justice system or other service providers, to have a history of physical abuse, and to be treated in outpatient programs. They had lower levels of alcohol severity, but did not differ with regard to psychiatric severity or criminal involvement. Primary users of methamphetamine were disproportionately represented among this group and had a distinct profile from primary alcohol- and opiate-users. Conclusion: Study findings suggest that mothers involved with child welfare enter substance abuse treatment through different avenues and present a clinical profile of treatment needs related to exposure to physical abuse, economic instability, and criminal justice involvement.