Prader-Willi Syndrome (PWS) is the most common known genetic cause of life-threatening obesity in children. Although the cause is complex it results from an abnormality on the 15th chromosome. It occurs in males and females equally and in all races. Prevalence estimates have ranged from 1:8,000 to 1:25,000 with the most likely figure being 1:15,000. PWS typically causes low muscle tone, short stature if not treated with growth hormone, incomplete sexual development, motor and social development delays and a chronic feeling of hunger that, coupled with a metabolism that utilizes drastically fewer calories than normal, can lead to excessive eating and life-threatening obesity. The food compulsion makes constant supervision necessary. Children with PWS can be sweet and loving, but they display characteristics of the Prader-Willi personality that can cause social and behavioral problems. They also have many complex and unique medical issues. With knowledge, support and understanding, persons with PWS can and do become valued members in our communities. They need to be supported by parents, care givers and professionals who have the knowledge and tools needed to assist them in doing this. PWSA of Michigan provides a variety of services to make this possible.