This survey is one component of the Monitoring Medicare+Choice Project, a national study designed to provide information on health insurance decisions made by Medicare beneficiaries. Funded by the Robert Wood Johnson Foundation, the project examined how Medicare beneficiaries responded to the implementation of the Medicare+Choice provisions of the Balanced Budget Act of 1997. Among their multiple objectives, the Medicare+Choice provisions sought to expand substantially the types of coverage choices available to Medicare beneficiaries and to encourage beneficiaries to think more actively about these choices. The Medicare+Choice Survey interviewed a sample of Medicare beneficiaries about their basic knowledge of Medicare, current Medicare coverage options, sources of supplemental insurance coverage, satisfaction with current coverage, reasons for the most recent change in Medicare coverage or lack of change since September 15, 1999, sources of information used to make their coverage choices, and salience of the choice and its most relevant considerations. Additional information collected by the survey included the respondent's health and functional status, age, sex, marital status, race, Hispanic origin, education, reading ability, household income and the number of people supported by that income, and language spoken at home.