The objective of the study was to study differences in aging phenomena among adults with intellectual disability (ID), who live in community residence versus their peers in residential care centers and to determine the contribution of health status, age, gender, etiology and level of ID to the decline in ADL function with age. Our study was based on matched pairs between persons with ID in community residence (N = 101) and their peers living in residential centers (N = 101) by age, gender, etiology and level of ID. Fifty-three percent were aged 40-49 years, 23% were aged 50-59 years and 14% were aged 60-71 years. Ten percent had Down syndrome (DS), 16% had cerebral palsy (CP) and the rest had ID with no specific etiology (NSID). Caregivers were interviewed to ascertain health problems, sensory impairments and activity of daily living (ADL). The type of residence alone could not explain the morbidity and health problems of adults with ID, which were affected by age and etiology. Participants with NSID functioned better than those with Down syndrome or cerebral palsy in all ADL areas. MANOVA and regression analysis indicated that age and health status did not contribute to the explained variance of the ADL function of the participants without specific etiology. The CP group had the most vulnerable etiology exposed to medical problems and decline in ADL function with age. Action should be taken to increase the awareness of the staff to health deterioration that can occur among adult persons with ID, especially among various types of etiologies, such as DS and CP. (Contains 5 tables.)