Although maladaptive and compulsive behaviors are increasingly well-described in young persons with Prader-Willi syndrome, it is unclear how these problems manifest in older adults with this syndrome. In Part I, I compared maladaptive and compulsive behaviors in 45 older adults with Prader-Willi syndrome (ages 30 to 50 years) to 195 children, adolescents, and young adults. Young adults were at highest risk for problems. In contrast, maladaptive and compulsive symptoms diminished significantly in older adults with Prader-Willi syndrome. In Part II, I examined predictors of problems other than age: IQ, gender, BMI, and-for adults-living status. Gender and BMI were significant predictors of skin-picking and other symptoms. Possible reasons are discussed for sweeping declines in problems among older adults.