The paper examines the recent reforms of health insurance in Chile and Argentina. These partially replace social health insurance with individual insurance administered through the private sector. In Chile, reforms in the early 1980s allowed private health insurance funds to compete for affiliates with the social health insurance system. In Argentina, reforms in the 1990s aim to open up the union-administered social insurance system to competition both internally and from private insurers. The paper outlines the specific articulation of social and individual health insurance produced by these reforms, and discusses the implications for health insurance coverage, inequalities in access to healthcare, and health expenditures.