Centers for Medicare & Medicaid Services | 603,633 followers on LinkedIn. Transforming the Future of America's Health Care | The Centers for Medicare & Medicaid Services (CMS), a federal agency within the U.S. Department of Health and Human Services, is one of the largest purchasers of health care in the world. Medicare, Medicaid, the Children's Health Insurance Program (CHIP) and the Health Insurance Marketplace provide coverage for more than 160 million Americans.