In the global fight against climate change, cap-and-trade programs remain one of the most effective means of greenhouse gas mitigation at policymakers’ disposal. Within the United States, several sub-national cap-and trade programs have emerged with varying degrees of success, the most noteworthy being the multi-state Regional Greenhouse Gas Initiative (RGGI). Recently, the state of Virginia began the process of joining RGGI through executive action, a process which has illustrated both barriers to and catalysts of state-level climate policy adoption. Utilizing Kingdon’s multiple streams framework, I conduct a case study to uncover the internal dynamics of the RGGI adoption process in Virginia. Ultimately, I find that partisan polarization surrounding environmental issues represents the largest barrier to state-level climate policy enactment. Additionally, I emphasize the importance of dedicated climate policy entrepreneurs to the adoption process and highlight the potential weakness of unilateral executive-driven policy adoption.