Child protection authorities in many countries are concerned with reducing the rates of investigations and with diverting at‐risk families from the child protection service system. In several countries, differential responses have been introduced into child protection law providing service providers with some choice between investigative or family support pathways, depending upon the level of risk posed in the circumstance. In this paper, we report on a study into a form of differential response known as Intervention with Parents' Agreement introduced in Queensland, Australia, in 2005. A unique feature of this differential response is that it occurs after an initial child protection investigation, although it does provide child protection services with options for providing supportive interventions to at‐risk families to prevent the further escalation of concerns. In this paper, we analyse practitioners' perceptions of factors that inhibit and promote implementation of the Intervention with Parents' Agreement. Drawing upon interviews with 25 practitioners, we identify factors that become important for securing participation after an initial investigation has occurred. We discuss the implications for the development of differential responses in child protection service systems.