Adults with intellectual and developmental disabilities often experience premature aging and high levels of frailty. Frailty characterizes health complexities and identifies adults with increased risks for adverse outcomes. This paper compared the prevalence of frailty amongst adults (aged 18–99 years) with and without intellectual and developmental disabilities. Frailty was measured using the Frailty Marker, based on the Adjusted Clinical Groups‐Predicative Model, and was compared between a cohort of 51,138 adults with intellectual and developmental disabilities and a random sample of 3,272,080 adults without intellectual developmental disabilities. Approximately 9% of persons with intellectual and developmental disabilities were frail, compared to only 3% of persons without intellectual and developmental disabilities. Women, older adults, and adults with mental illness or addiction(s), were more likely to be frail. Adults with intellectual and developmental disabilities are increasingly vulnerable as they age. However, to appropriately characterize frailty in this population, measures should be more inclusive of health characteristics and fluctuations that are related to frailty. Future research should investigate alternative measures of frailty for persons with intellectual and developmental disabilities, including measures derived from standardized health assessments, to meet the needs of the aging population.