The relationship between parental misuse of alcohol and/or illegal drugs and child maltreatment has received considerable attention in the United States, while comparatively few British studies have been published. In both countries research suggests that it is a large and growing problem and that it has a significant negative impact on children. In the current study, parental substance use, as defined by social workers, was considered by social workers to be a cause for concern in 52 percent of the families studied. Alcohol (in 24 percent of all families) and heroin use (in 16 percent) were the primary substances of concern. Substance misuse was strongly related to neglect, and cases were twice as likely to be subject to care proceedings. Very little involvement of substance misuse professionals in child protection procedures was found. Different profiles of social work concern were found for alcohol and for illegal drugs. Reasons for this difference and areas for further research are discussed. 2 tables and 30 references