Care for beneficiaries with chronic illnesses, such as heart disease and diabetes, is a major expense to the Medicare program, and a major detriment to beneficiaries’ quality of life. The Medicare Coordinated Care Demonstration is testing whether case management and disease management programs can lower costs and improve patient outcomes and well-being in the Medicare fee-for-service population. This publication, the source for a recent report to Congress, details findings from 15 programs during the first two years of Mathematica’s study, the largest random assignment study to date of disease management/case management programs. The report focuses on program impacts over the first year after enrollment for beneficiaries who enrolled during the first year, and over the first 25 months of operation for all enrollees. Findings include program-specific estimates of impacts on survey-based measures of patients’ health status, knowledge, behavior, satisfaction with their health care, quality of care, and quality of life; and claims-based measures of patients’ Medicare service use and expenditures, and the quality of care received. The findings in brief indicate that patients and physicians were generally very satisfied with the program, but few programs had statistically detectable effects on patients’ behavior or use of Medicare services.