Since its institutional birth in 1947, the GATT/WTO (WTO) has mushroomed from twenty-three original contracting parties to one hundred and fifty seven members as of September 2012. Another twenty-eight countries are currently observers, each at varying stages of the accession process. WTO members and observers cover some ninety-nine per cent of the world's population and over ninety-nine per cent of global trade. However, there are still fourteen states outside the multilateral rules-based trading system. This paper argues that existing explanations of membership and accession do not fully explain why these states remain outside the WTO, with implications for membership in international institutions generally. The paper tests hypotheses of non-membership based on a lack of willingness (domestic support), ability (technical capacity), and a lack of external pressure, and augments these statistical findings with a comparative country-level narrative of WTO (non)-accession decision making in two small island countries.
