In May 2011, a year after the passage of the Affordable Care Act (ACA), Vermont became the first state to lay the groundwork for a single-payer health care system, known as Green Mountain Care. What can other states learn from the Vermont experience? This article summarizes the findings from interviews with nearly 120 stakeholders as part of a study to inform the design of the health reform legislation. Comparing Vermont's failed effort to adopt single-payer legislation in 1994 to present efforts, we find that Vermont faced similar challenges but greater opportunities in 2010 that enabled reform. A closely contested gubernatorial election and a progressive social movement opened a window of opportunity to advance legislation to design three comprehensive health reform options for legislative consideration. With a unified Democratic government under the leadership of a single-payer proponent, a high-profile policy proposal, and relatively weak opposition, a framework for a single-payer system was adopted by the legislature — though with many details and political battles to be fought in the future. Other states looking to reform their health systems more comprehensively than national reform can learn from Vermont's design and political strategy.