In an age in which international relations are said to have succumbed to the sway of economic forces and considerations, the life and activities of ASEAN attest forcefully to the stubborn refusal of factors and calculations essentially political and strategic in nature to fade away. Even when economic cooperation was hurried along after 1975, the main impetus came from regional and global developments which were thought to convey important political and strategic messages and implications. As a regional organisation ASEAN is nonetheless predicated on the assumption that economic cooperation also matters, and in this chapter I shall explore various aspects of economic cooperation and relations in the region, and between the region and the outside world. No attempt will be made, however, to delve into the many and complex technical aspects of the economic issues involved. These are better left to the specialist economists. Rather the emphasis will be on certain factors which have a heavy bearing on the economic side of regional cooperation but which seldom have found their way into the discussions of those economists who have addressed the question of regional economic cooperation in Southeast Asia.