The rising tensions in the South China Sea have mainly been affected by China's growing confidence in its ability to challenge and redefine norms that constitute the regional structure. As China rises, Beijing comes under increasing pressure to accept prevailing international norms or, if it challenges existing norms, to provide an alternative source of legitimacy for its behaviour. This chapter, therefore, examines which norms China challenges and why it does so. Both the process of norm selection and norm contestation are analyzed. The main argument is that, from the Chinese perspective, what matters most when challenging norms is not the content of the challenged norm, but the likelihood of successfully shaping a new norm and thus becoming an effective standard setter in the region.