To meet its goal of providing comparative plan information to Medicare beneficiaries, the Health Care Financing Administration invested in developing the Consumer Assessments of Health Plans Study (CAHPS) survey of beneficiary enrollees in Medicare Managed Care (MMC) plans. This article describes the process through which the MMC survey was developed, and examines issues in using this Medicare beneficiary survey that have implications for all CAHPS surveys. Cognitive interviews and a field test were conducted with Medicare beneficiaries. A sample of individuals was selected from six health plans. The use of screening questions, skip instructions, and tailored "not applicable" response options appeared to facilitate the response task. Some CAHPS access questions were not meaningful to Medicare beneficiaries. Data do not support the need to adjust for length of plan enrollment. Analyses suggested changes to improve the MMC survey and to make other CAHPS surveys consistent with these changes.