Since the Cold War, South-East Asia has been marked by a period of relative calm and stability. Yet this peace belies ongoing tensions, mistrust and stress in the Association of Southeast Asian Nations (ASEAN) and among its member states. Within the scholarship on ASEAN, not enough attention is devoted to these underlying currents. How and in what way do tensions stress the ASEAN norms? What are some of the coping mechanisms adopted by ASEAN and its member states? Engaging with the scholarship on norms, the author contends that changes wrought in this relationship are both extra- and intra-mural. These have accelerated as contentious issues—particularly the South China Sea disputes—gain more visibility. The author argues that ASEAN is put under pressure, firstly, through a more muscular Chinese foreign policy that disrupts but does not yet break the fundamental norms of ASEAN and, secondly, through internal contestation over ASEAN norms that challenges the meaning of these norms. Essentially, the article gives an account of how internal and external pressures are burdening ASEAN norms but yet remain durable because of resistance against duress by the bloc and member states. This is done through an examination of instances where the established order and practices in the region were disturbed, and the response to this disturbance.