Thailand achieved universal health coverage (UHC) with three public health insurance schemes in 2002. This study examined how political economy factors influenced the evolution of public health system reform in Thailand by applying the political economy framework. This study concluded that, although path dependency played an important role in exerting pressure on resistance to change, the reform team’s ability to generate and effectively use evidence to guide the political decision-making process helped place the reform on such a “good path” that it was able to overcome opposition.