While questions have been asked about whether ASEAN could, or even should, adopt the United Nation's Women Peace and Security (WPS) agenda, this article is the first to ask why it has not done so already. ASEAN's strong engagement with gender issues beyond the WPS agenda, together with the pressing need to address conflict and security concerns within Southeast Asia, make this an absence that requires an explanation. I argue that the usual explanatory framework deployed to account for ASEAN "not doing" something - the weaknesses caused by consensus, unanimity and the "ASEAN Way" - do not explain the absence of the WPS agenda; ASEAN's engagement with gender is too advanced for the "it does not want to" explanation to hold. Instead, I locate the failure to engage with the WPS agenda in a particular elite understanding of women as both non-political and vehicles for the realization of economic and social well-being. This elite mindset, which both differs from that found within the ASEAN institutions dedicated to gender issues and which serves as the key driver of ASEAN's institutional design, has retarded engagement with WPS because it stands at odds with the active political agency of women that WPS promotes. Revealing this reason for ASEAN's failure to institutionalize WPS provides a way to consider the future of this important set of norms. I argue that efforts to mainstream WPS must take account of this ingrained framing of women as apolitical if they are to be successful.