Abstract Background 20% of all children suffer a neurodevelopmental delay or disorder (NDDD) worldwide. Early multidisciplinary diagnostics, early intervention and timely diagnostics along the rehabilitation trajectory are needed to improve the child’s functioning and participation. In Flanders, Belgium, 6 types of public organizations (164 service points in the region) offer multidisciplinary diagnostics of NDDD for children. However the objective of timely diagnostics for the population is not realized. Methods A qualitative thematic analysis identifies the criteria of Federal and Flanders’ regulations for publicly accredited and funded organizations providing multidisciplinary diagnostics for children with (suspected) NDDD. A survey was sent in different settings on waiting periods and perceived determinants hampering early diagnostics These results were discussed and validated by experts in focus groups. Results Average waiting times for diagnostics run up to 1 year before a diagnostic trajectory can be started. Regional differences occur in the availability of diagnostic services. Formal regulations hamper the development of collaborative networks and an integrated health services model offering accessible diagnostics along NDDD trajectories. The field lacks public health services strategies to provide accessible, efficient and effective diagnostics for a complex range of NDDD target groups Conclusions Coordination of services providing multidisciplinary diagnostics for children with (suspected) NDDD is needed. A health services approach supporting mandated regional networks will improve the accessibility of early and timely diagnostics. Key messages Development of collaborative networks of different types of services offering diagnostics will improve the accessibility of early and timely multidisciplinary diagnostics for children with NDDD. Better accessibility to multidisciplinary diagnostics will improve long term outcome for children with NDDD.