This report provides results from an investigation of comparative disability risks of specific chronic physical and mental illnesses, diseases, and impairments. National estimates are presented of the risks of chronic health conditions causing disability--including activity limitation, work disability, and need for assistance in basic life activities--based on an analysis of data from the National Health Interview Survey (NHIS), a continuing survey of the health of the noninstitutional United States population. Risks of disability are estimated and compared for 62 specific chronic health conditions or groups of health conditions adjusted for age, gender, and other social and demographic factors. Major highlights of the report include: (1) most chronic conditions do not have high risks of disability (about 11.7 percent cause activity limitation); (2) the risk of disability is inversely related to prevalence of chronic conditions; (3) the epidemiology of disability is quite different for children than for adults; (4) risks of disability increase with age for most conditions (e.g., risk of chronic conditions causing work limitation is 4.3 times higher at ages 45-69 than at ages 18-44); and (5) mental illness conditions have low to moderate risks of causing disability, compared to physical health conditions. Extensive tables detail the report's findings. (Contains 39 references.) (DB)