High rates of child abuse and neglect occur in many families in which either or both parents abuse illicit drugs. This study reports on the results of a randomized controlled trial with families having a parent on methadone maintenance (N = 64), in which an intensive, home-based intervention, the Parents Under Pressure (PUP) program, was compared to standard care. A second brief intervention control group of families received a two-session parenting education intervention. The PUP intervention draws from the ecological model of child development by targeting multiple domains of family functioning including the psychological functioning of individuals in the family, parent-child relationships, and social contextual factors. Mindfulness skills were included to address parental affect regulation, a significant problem for this group of parents. At 3- and 6-month follow-up, PUP families showed significant reductions in problems across multiple domains of family functioning, including a reduction in child abuse potential, rigid parenting attitudes, and child behavior problems. Families in the brief intervention group showed a modest reduction in child abuse potential but no other changes in family function. There were no improvements found in the standard care group and some significant worsening was observed. Results are discussed in terms of their implications for improved treatment.