Down Syndrome Education USA -is developing and evaluating education programs, organizing conferences for families and professionals and supporting practical scientific research

Down Syndrome Online, offers comprehensive information about Down syndrome, including articles, books and scientific papers

International Mosaic Down Syndrome Association, Support, research and advocacy for those with Mosaic Down Syndrome (a variant of Down Syndrome representing about 2-4% of Down Syndrome cases)

National Association for Down Syndrome, NADS is the oldest organization in the country serving individuals with Down syndrome and their families. Their mission is to ensure that all persons with Down syndrome have the opportunity to achieve their potential in all aspects of community life. They offer information, support, and advocacy.

National Down Syndrome Congress, The mission of the NDSC is to provide information, advocacy and support concerning all aspects of life for individuals with Down syndrome.

National Down Syndrome Society, The mission of the National Down Syndrome Society is to be the national advocate for the value, acceptance and inclusion of people with Down syndrome.

National Mosaic Down Syndrome Association is a new organization devoted to support and research of this form of Down syndrome.