This study describes service users with Down syndrome (N = 1,199) and a comparative sample with intellectual and developmental disabilities but not Down syndrome (N = 11,182), drawn from National Core Indicator surveys of adult service users in 25 U.S. states. Individuals with Down syndrome were younger than were individuals without Down syndrome. Men with Down syndrome were older than women with Down syndrome, whereas the reverse was true of the individuals without Down syndrome. Most (68%) people with Down syndrome had mild or moderate intellectual disability. The prevalence of vision impairment, hearing impairment, and physical disability increased with age. Adults with Down syndrome were more likely to have Alzheimer's dementia, have a hearing impairment, or be overweight, but they were less likely to have a physical disability than those without Down syndrome. Adults with Down syndrome were less likely to live in institutions or their own home, but they more likely to live in a family member's home. The results of a logistic regression showed that participants were more likely to be reported to be overweight if they had Down syndrome, were female, and were physically inactive, but they were less likely to be reported to be overweight if they were older, had more severe intellectual disability, had cerebral palsy, or were not independently mobile.