Drawing on in-depth interviews with representatives from 17 organisations, this paper focuses on patterns of collaboration between different actors involved in the pre- and post-adulthood trajectories of youngsters arriving in Belgium as unaccompanied refugee minors. First, we clarify that the Belgian support system for these minors is characterised by fragmentation. In order for this fragmented system to benefit minors, different actors need to collaborate closely. Our qualitative analysis reveals that there is room for progress, specifically when concerning information exchange, case transfer and case coordination among different organisations. We identify five different but interrelated factors that engender interprofessional collaboration: timely and adequate diagnoses; knowledge of all service providers; sufficient capacity; informal trust relationships between professionals; and cultural competence of social workers and other professionals. While some of these issues can be addressed at the level of individual organisations, many are also embedded in a structural context of time pressure, understaffing, increased stress levels and high personnel turnover.