A sizeable portion of families involved with the child welfare system deal with parental substance abuse issues. This study examined the role of child welfare and substance use treatment systems, and their support of pregnant women and mothers with substance use problems. Qualitative interviews were conducted with 24 managers and direct service staff from both substance use treatment and child welfare fields. The purpose was to examine factors that assist or inhibit collaboration of the two fields. Findings indicate that contextual factors influencing collaboration between systems are affected by policy, practices and cultural norms. The following factors were suggested as influencing collaboration: use of harm reduction; changes in child welfare policy resulting in inconsistent practices; a “forced” integration of services between substance abuse and child welfare resulting in fear of unintended consequences because of the close proximity of services; regional differences where in rural areas families will have one worker who performs several roles, whereas in urban areas families will have different workers according to the need; and, in a direction that contradicted expectations, efforts to increase integrated services. Factors that facilitate collaboration between systems include: principles and values; processes and protocols; program and practice innovation; and shared outcomes. Participants discussed variables, which impede cross-collaboration. Explicitly, disconnection between systems, disconnection between principles and practice, problematic communication flow, rigid orientation to practice, and scarcity of resources were found to inhibit connection between systems. Authors suggest future research should examine in greater depth how harm reduction models may be utilized within a child welfare context in order to provide support for caregivers and children and ultimately increase positive outcomes.