Fragile X syndrome (FXS) is the leading inherited cause of mental retardation. In this article, we review what is known about the language and related problems of individuals with FXS. In doing so, we focus on the syndrome-specific features of the language phenotype and on the organismic (i.e., genetic and individual neurocognitive and behavioral)…

Down syndrome (DS) is associated with abnormalities in multiple organ systems and a characteristic phenotype that includes numerous behavioral features. Language, however, is among the most impaired domains of functioning in DS and, perhaps, also the greatest barrier to independent meaningful inclusion in the community. In this article, we review…

When developmental concerns arise in children, a clinical assessment focuses on the child's developmental profile to achieve three goals (1) determine diagnosis, (2) develop interventions, and (3) evaluate progress. Parents often have needs during this time that are not addressed by professionals because of the exclusive focus on the child during…

In this article, we consider the theoretical debates and frameworks that have shaped research on language development and intervention in persons with mental retardation over the past four decades. Our starting point is the nativist theory, which has been espoused most forcefully by Chomsky. We also consider more recent alternatives to the…

This article seeks to elucidate the trajectory of development in adolescents and adults with autism. Prospective, retrospective, and cross-sectional studies are reviewed to reveal the manifestation of and changes in the core symptoms of autism in adolescence and adulthood. Comparing children with adolescents and adults, modest degrees of symptom…