Provides an overview of some of the key economic and institutional issues confronted during the implementation of health insurance reforms, and articulates the concept of scaling up social health insurance (SHI) as a dynamic process that offers a path out of a fragmented and failed health care market, based on ability and willingness to pay by large segments of the population, to an integrated, universal system, based on mandated, often means-tested, contributions. The path from fragmentation to integration is punctuated by milestones set by each country's political, economic, social, and institutional realities. A proposed typology for different health insurance systems includes critical elements such as population coverage and depth of the benefits package and the institutional structures of organizations involved and governance arrangements. The true nature of large government-mandated health insurance systems is often defined by the accountability and choice over the use of mandatory contributions and supply of services.