Medicare is specifically mandated to provide health care services to elderly and/or disabled United States residents, as well as those with end stage renal disease. Although Medicare has been successful in dramatically improving both the access to care and the overall health of its constituents, studies have shown inequalities in care associated with the race/ethnicity of Medicare beneficiaries. On the surface, Medicare health maintenance organizations (HMOs) appear to address some of the factors associated with these inequalities, however, the Medicare HMO program, now called Medicare+Choice (M+C), is itself undergoing substantial program changes as a result of the Balanced Budget Act (BBA) and subsequent revisions, e.g., the Balanced Budget Revision Act (BBRA) and the Benefits Improvement and Protection Act (BIPA). This study has two broad objectives. First, we will determine individual level characteristics related to M+C plan enrollment among elderly White, Black, and Hispanic Medicare beneficiaries, whether the factors which elderly Black and Hispanic beneficiaries report as influencing their enrollment in HMOs differ from those that influence elderly White Medicare beneficiaries, and whether elderly Black and Hispanic beneficiaries enrolled in HMOs differ from HMO enrolled elderly White beneficiaries in terms of their self-reported health, use of health care, and perceived access to care. Second, we will examine the availability of Medicare HMOs and benefit packages for beneficiaries of differing race/ethnic classifications, how HMO enrollment rates are related to race/ethnic classification and range of plan benefits, and how the availability of HMOs and HMO enrollment by different race/ethnic groups changed subsequent to implementation of BBA provisions. We will use both survey and population-based (using Medicare administrative data and other population-based data) methodologies to examine individual and system level factors affecting access to and use of medical care, the availability of plans and services, and plan selection by enrollees. This study will provide the first comprehensive examination of both individual and system level factors affecting minority use of the Medicare HMOs, and will provide needed information on how the evolving Medicare system is affecting health care for Black and Hispanic Medicare beneficiaries.