How are regional organizations responding to the emergence of nontraditional security (NTS) challenges? Are they engaging in more cooperative efforts to meet new threats? Or, on the contrary, do they react in different manners according to their distinctive values, principles and internal structures? This article attempts to investigate how the threats posed by NTS are compelling different regional organizations to reconsider their security thinking and to find new innovative ways of cooperation. This is done by comparing two diverse regional organizations, the EU and the Association of Southeast Asian Nations (ASEAN), whose models of security cooperation have significantly varied reflecting the preference for different security approaches. The EU's security system has been more formalized and institutionalized; conversely, the "ASEAN way" has traditionally been rooted in the principles of informality and consensus. It is argued, however, that the emergence of NTS threats is acting as a catalyst behind a normative and operational shift of the modus operandi of both organizations. In so doing, this empirical analysis will try to shed light on the effects of exogenous factors on the emergence of patterns of convergence within the security sphere of distinctive regional processes.