The processes used by social workers to collect, interpret and use stakeholder information in child protection cases are an unexplored but essential part of the decision-making process. This study focuses on social workers' efforts to integrate the knowledge of other professionals. This article draws on a framework for managing knowledge across organisational boundaries and a process-oriented conceptualisation of knowledge integration. The analysis of ten interviews with social workers shows that the process of knowledge integration affects the basis of social workers' decision making. We argue that knowledge possessed by other professionals is often viewed as easily transferrable and correctly received, when in fact this knowledge is often complex and subjective and requires extra effort to obtain, understand and integrate into case-specific situations. This implies a need to recognise information processing as an influencing factor in decision making within child protection that pertains to both practice and research. Our study is based on ten in-depth interviews with child protection social workers. We focus on the significance of the process of collecting and interpreting information from other professionals (boundary work), information which contributes to the social workers' assessments and decision making. We found that despite the efforts made by the social workers to obtain and understand knowledge from other professionals, this knowledge transfer had limitations. These limitations can weaken the foundation upon which decisions in child protection services are made. We suggest that: (i) child protection services pay more attention to the boundary work; at the organisational level by facilitating collaboration between organisations and at the individual level by enhancing the social workers' interpersonal collaborations skills and (ii) child protection research should include boundary work as an influencing factor on the decision-making process.