There is significant variation in experiences with M+C across the United States. In some areas of the country, beneficiaries have a choice of multiple managed care plans and M+C market penetration rates remain well above the national average. Phoenix, Arizona is one of the markets where M+C appears to be successful. Thirty-seven percent of eligible beneficiaries are enrolled in a managed care plan and beneficiaries can choose from eight plans offered by six firms. Success of M+C in Phoenix has been partially attributed to a long history of managed care in Maricopa County, especially in the Medicaid program. The new Medicare reform legislation envisions a large role for private plans in Medicare?s future, which makes it important to understa...