The international conference on Down syndrome will be held in the United States under the auspices of the National Down Syndrome Society. The conference will be convened under the direction of the NDSS Science Advisory Board, in collaboration with a Conference Organizing Committee. The meeting will review and document the current status of research on behavior and cognitive function in Down syndrome, including an overview of current neuroscientific research and the use of animal models. It will also review current knowledge about applying research findings to early stimulation and education programs that aim to optimize the status of individuals with Down syndrome. Finally, it will explore the directions that future research of this disorder should take. Plenary sessions will be organized in terms of five developmental stages, with each covering a variety of major topics including: 1. neurobiology and animal models 2. cognitive development and function 3. learning and memory capacity 4. language development and function 5. motor development 6. social behavior and emotional development 7. patterns and mechanisms of developmental change. There will also be a poster session for scientists to present work on specific related topics. This session will be particularly focused on younger investigators. The meeting will provide an opportunity for participants to interact with colleagues, synthesize and share knowledge, develop new collaborations and generate ideas about practical applications. This opportunity should facilitate progress in research and practice on Down syndrome.