In the absence of complete public surveillance data, estimating the prevalence and needs of sub-groups of heterogeneous populations is nonetheless critical to properly inform health and social services planning and policy. We thus introduce market segmentation as an innovative tool for health and social services planners and policy makers. Segmentation is a process whereby broad populations are categorized into sub-groups with common characteristics and needs. Using the example of autism spectrum disorder and/or intellectual disability in Quebec, Canada, we triangulate available data and mathematical problem solving to present a portrait of the varying support needs of this under-served, yet growing, population.