What has caused the rising gap in health insurance coverage by education in the U.S. over the last thirty years? How does the employment-based health insurance market interact with the labor market? What are the effects of social insurance such as Medicaid? By developing and structurally estimating an equilibrium model, I find that the interaction between labor market technological changes and the cost growth of medical services explains 60% to 70% of the gap. Using counterfactual experiments, I also evaluate the impact of further Medicaid eligibility expansion and employer mandates introduced in the Affordable Care Act on labor and health insurance markets.