An insight into the EU’s role in developing security cooperation with Myanmar via two key areas: the ASEAN Regional Forum (ARF) and the aftermath of Cyclone Nargis ravaging Myanmar’s Irrawaddy delta, begs several questions. The insight concerns the period starting when Myanmar joined ARF, in 2004, and ending when Nargis hit, in 2008. The EU’s role is explored through the co-chair’s summary reports of the meetings that the EU co-chaired with ASEAN. A mix of social mechanisms (Checkel 1999, 2005), logic of consequences and appropriateness (March and Olsen 1995, 1998, 2004) and observations derived from interviews (Southeast Asia and Brussels), in a combined relationship, explain the reactions of ASEAN, Myanmar and the EU to Cyclone Nargis. What are the relationships of these explanatory tools? Is Checkel’s argument more persuasive than March and Olsen’s? Do any of these frameworks possess greater causal weight than the other? Do we need all three? Does this insight add a particular nuance to these theories or it further demonstrates that these theories are useful?