Medicaid—a federal/state partnership with shared authority and financing—is currently a public health coverage program for low-income children, their parents, the elderly and people with disabilities. Medicaid pays for health and long-term care services for more than 55 million people. Although participation is optional, all 50 states participate. Section 1115 of the Social Security Act gives the secretary of Health and Human Services authority to waive provisions of the law to encourage state innovation and experimental demonstrations in Medicaid. States have tested a wide range of policy approaches under 1115 waivers, including offering coverage to otherwise ineligible populations, providing services not typically covered by Medicaid, experimenting with cost sharing and other payment reforms, and implementing changes to the delivery system. In 2012, 30 states and the District of Columbia are operating at least one 1115 waiver.