This article analyses Vietnamese strategies to constrain China in the South China Sea. It tests Brantly Womack's theory of asymmetry as a framework for analysing bilateral relations. Mature asymmetry exists when the weaker state gives deference to the more powerful state in return for the stronger state's recognition of the weaker state's autonomy. Vietnam attempts to achieve this balance through a process of "struggle and cooperation" with China on key issue areas. Vietnam pursues three strategies to manage its relations with China: codification of bilateral relations through high-level visits by party and state leaders; enmeshment of China in a web of cooperative relations including economic ties: and self-help, particularly military modernization. This article analyses the bilateral mechanisms that structure political, economic and defence relations. The party mechanisms include summit meetings, exchange visits by party commissions and ideological seminars. State-to-state relations are managed by a Joint Steering Committee at deputy prime minister level and comprise a dense network of ministerial exchanges. Defence relations are managed at ministerial level and include senior high-level visits and a range of defence cooperation activities including joint ship patrols and naval port visits. The article concludes with a discussion of tensions arising from territorial and sovereignty disputes in the South China Sea. In summary, the "tyranny of geography" dictates to Vietnam that it judiciously apply the levers of cooperation and straggle through various party state, military and multilateral structures in order to better manage its relations with China. Keywords: China, Vietnam, asymmetry, South China Sea, autonomy.