The assessment of support needs of children with an autism spectrum disorder and their families has been hindered by the ambiguity surrounding the definition of need and the lack of a conceptual framework to guide investigations. This paper examines two major approaches to measuring need and discusses their appropriateness for use in autism. We focus on school-aged children, because of the relative lack of research in this area and the challenges of measuring need in children with an autism spectrum disorder in this age group. A conceptual framework, which explores parents' perceived need, is proposed. We suggest that the child's adaptive skills and challenging behaviors will be important in predicting the extent of the parent's perceived unmet need. (Contains 1 figure.)