The 10-member Association of Southeast Asian Nations, ASEAN, is arguably the most durable and successful regional grouping in the developing world. Established in 1967, it has contributed greatly to regional harmony and prosperity. The Association is characterized by great internal diversity, generally high economic growth, and a reluctance to establish a strong supra-national organizational structure. Beginning in 1976, the member countries have initiated a range of economic cooperation and integration programs, initially for merchandise trade, in the 1990s focusing on services trade, investment and labour, and in the past decade extending to some broader macroeconomic and financial measures, the latter in cooperation with its Northeast Asian neighbours. Its members have adopted what appear to be formal preferential trade arrangements, but in practice these have usually been multilateralized. ASEAN has informally practised what is sometimes termed ‘open regionalism’. There is little likelihood in the foreseeable future of it adopting deep EU-style economic integration behind a common external trade regime.