Abstract Background and Aim In the Netherlands about one in seven 1- to 11-year-old children are overweight. The multifaceted nature of childhood overweight requires joining forces across the medical, social and public sector. This study evaluated an integrated network approach of preventive care (INPC) for overweight children focusing on the process of intersectoral professional collaboration. Methods Fourteen network partners from the three sectors were interviewed face to face with semi-structured topic lists to determine the extent of collaboration in and outside sectors, the perceived outcomes and the hindering and facilitating factors. Results Collaboration within each sector was adequately established and all partners were in contact with the central care provider who functions as linking pin in the INPC. However, collaboration across sectors was not optimally realized. Both the medical and public domain partners indicated to have minimal contact with professional partners from the social domain, while they were perceived important in the INPC. Main hindering factors were related to the complexity of the childhood overweight problem, a lack of knowledge about network partners, unclarity in referrals, feedback, roles and responsibilities. In addition, frequent changes in policy, in personnel, lacking a visible leader, funding and time, were also hindering. Facilitating factors were: a general positive attitude towards intersectoral collaboration, knowing each other, short communication lines, a shared vision, trusting each other's expertise, and also formalized agreements and local health policy, and periodic meetings with partners. Conclusions Realizing professional collaboration across domains to tackle childhood overweight requires specific attention to structural factors enabling professionals to do so in their daily work. Stable funding and policies, clear responsibilities on the one side, getting to know each other, trust and positive attitudes on the other. Key messages An integrated approach for ...