Organisations subsidized by the government to perform diagnostic evaluations of children with a (suspected) develop- mental disorders. data were thematically analysed and categorized in a process of researcher and data-triangulation. a member check validation was done. results: 59 persons participated. we classified the hampering and facilitating factors for collaboration current interorganisa- tional collaboration is mostly limited to referral. organisational differences in vision and goals, working processes and quality requirements, regulations and financial support criteria, a problem of accessibility and communication problems are hampering factors. knowledge of mutual expertise and working processes, personal contacts and open communication are facilitating factors. conclusions: a population public health based organisation of the field of multidisciplinary diagnostic evaluations for children with a developmental disorder, with interorganisational collaboration and coordination of activities in mandated networks, sharing experience and knowledge, would increase the accessibility for all children and strenghten the health system. the implemen- tation of interorganisational networks would benefit from a functional and institutional analysis of organisations. key messages: coordination of activities and interorganisational collabora- tion in mandated networks, could potentially improve the accessibility of diagnostic evaluations for children with a developmental disorder. implementation interorganisational networks would benefit from a functional and institutional analysis of organisations