The prominence of private health insurance has been buttressed by government interventions directed at PHI markets in several OECD health systems, although the effectiveness of policies aimed at increasing market size and fostering outcome quality has differed widely. Australia, Ireland, the Netherlands, Germany, Switzerland and the United States have promoted and maintained a large and viable private health insurance market because policy makers have concluded that mixed public-private coverage systems can better deliver desired health policy and social outcomes. These governments have used regulation18 and fiscal instruments to steer and encourage PHI markets. In Ireland and Australia, regulation has been one main factor in encouraging consumer demand.