Most analyses of China's foreign and security policies treat China as a unitary actor, assuming a cohesive grand strategy articulated by Beijing. I challenge this conventional wisdom, showing how Chinese provinces can affect the formulation and implementation of foreign policy. This contributes to existing research on the role of subnational actors in China, which has focused on how they shape domestic and economic policies. Using Hainan and Yunnan as case studies, I identify three mechanisms of provincial influence – trailblazing, carpetbagging, and resisting – and illustrate them with examples of key provincial policies. This analysis provides a more nuanced argument than is commonly found in international relations for the motivations behind evolving and increasingly activist Chinese foreign policy. It also has important policy implications for understanding and responding to Chinese behaviour, in the South China Sea and beyond.