This article uses Organisation for Economic Co-operation and Development (OECD) data to assess whether a single-payer health system delivers more care at less cost than do other universal coverage models. Single-payer plans are defined as those that rely on a limited number of revenue sources and systems in which financing is concentrated and private insurance for hospital and medical services is limited. Single-payer advocates argue that this organizational model is best able to reduce administrative costs, control provider payments, and limit the supply of services. This analysis shows that single-payer-like systems do not do a consistently better job of controlling physician incomes but do achieve some administrative cost savings compared to more fragmented systems. Overall, single-payer systems are modestly less costly than their peers and spend a slightly smaller share of the gross domestic product (GDP) on health. There are, however, substantial variations both over time and across countries in the performance of the single-payer-like nations, as well as among the nations in the other universal coverage model categories. Overall, the differences in system performance among the universal coverage OECD countries are very small, while the difference between the performance of any one of these countries and the United States is enormous and persistent.