We review the literature on the prevalence and conditions resulting in overweight and obesity in people with intellectual disability (ID), followed by obesity treatment research with typically developing children and adaptations for children with ID. In addition to proposing directions for future research and practice, we report a comprehensive randomized control trial (RCT) of family-based behavioral intervention targeting weight loss among adolescents with Down syndrome. (Contains 1 figure, 1 footnote and 1 table.)