The Association of Southeast Asian Nations (ASEAN) has traditionally adhered to a strict principle of non-interference, but since the mid-1990s the principle has come under challenge from a variety of sources. One of the principal challenges has developed from the global normative shift away from the traditional understanding of state sovereignty as guaranteeing rights of non-interference towards acceptance of sovereignty as responsibility, the underlying premise of the responsibility to protect (R2P). As unanimously agreed by the UN General Assembly in 2005, R2P comprises each state’s responsibility to protect its own populations from genocide, war crimes, ethnic cleansing and crimes against humanity, the international community’s duty to assist states in this endeavour, and a responsibility for the international community to take timely and decisive action in situations where the host state has manifestly failed in its R2P. At first glance, the latter two elements of this principle seem to require behaviour that contradicts the principle of noninterference. This raises questions as to why R2P was endorsed by Southeast Asian governments and whether it can be ‘localised’ (Acharya 2009) in a region whose politics are underpinned by non-interference. There are three potential answers to this question. First, it could be argued that the region has rejected R2P in favour of non-interference but that it has tried to legitimise this rejection by simply ‘mimicking’ (Johnstone 2007) support for the norm. Second, it might be concluded that the region has jettisoned non-interference in favour of R2P. Third, it could be argued that processes of norm localisation are producing an accommodation between the two principles. This accommodation involves the formal retention of both principles but the subtle realignment of each in order to make them compatible and make support for both coherent. It is this third explanation, we argue, that best explains the relationship between R2P and noninterference in Southeast Asia. As other contributors to this handbook point out, R2P has been revised to limit its capacity to legitimise coercive interference, whilst non-interference is in the process of being recalibrated to permit expressions of concern, offers of assistance and even the application of limited diplomatic pressure in response to major humanitarian crises. Thus, whilst the region remains largely hostile to doctrinal revisions to non-interference, subtle changes are evident in practice.