The Foundation for Prader-Willi Research
- A non-profit group of volunteer families, friends and researchers aiming to raise funds for research into finding treatments.
- http://www.fpwr.org/

PWS Notes
- Designed to provide useful background on Prader-Willi Syndrome (PWS) for parents and to organize medical information that may be helpful for future research directions.
- http://www.pwsnotes.org/

The New Jersey Chapter of the Prader-Willi Syndrome Association
- Includes news, important dates, fund raising, maps and links.
- http://www.pwsausa.org/nj/

The Prader-Willi Syndrome Association (UK)
- Information and resources about this chromosomal disorder.
- http://www.pwsa-uk.demon.co.uk/

Prader-Willi Syndrome Association (USA)
- Characteristics include hypotonia, insatiable appetite, obesity if food intake is uncontrolled, hypogonadism and incomplete sexual development, developmental delays, variable degrees of mental retardation or functional retardation, short stature (adult)
- http://www.pwsausa.org/

Williams Syndrome and Prader-Willi Syndrome
- Diagnostic assessment, selected treatment services and opportunities to participate in research from the Yale University Child Study Center.
- http://info.med.yale.edu/chldstdy/wspws

Prader-Willi Alliance of New York
- Represents the interests of individuals in New York State with Prader-Willi syndrome, their families, and the professionals who provide services to the Prader-Willi population.
- http://www.prader-willi.org