In 2010, immediately before the United States of America (USA) implemented key features of the Affordable Care Act (ACA), 18% of its residents younger than 65 years lacked health insurance. In the USA, gaps in health coverage and unhealthy lifestyles contribute to outcomes that often compare unfavourably with those observed in other high-income countries. By March 2014, the ACA had substantially changed health coverage in the USA but most of its main features - health insurance exchanges, Medicaid expansion, development of accountable care organizations and further oversight of insurance companies - remain works in progress. The ACA did not introduce the stringent spending controls found in many European health systems. It also explicitly prohibits the creation of institutes - for the assessment of the cost-effectiveness of pharmaceuticals, health services and technologies - comparable to the National Institute for Health and Care Excellence in the United Kingdom of Great Britain and Northern Ireland, the Haute Autorité de Santé in France or the Pharmaceutical Benefits Advisory Committee in Australia. The ACA was - and remains - weakened by a lack of cross-party political consensus. The ACA’s performance and its resulting acceptability to the general public will be critical to the Act’s future.