Abstract Both in Asia Pacific and Latin America, considerable confusion and ambiguity surround the notion of 'open Regionalism' that question its relevance for practical purposes. Chapter I will examine various interpretations and applications of the concept and study under what circumstances the two elements 'open' and 'regionalism' come into contradiction. The chapter first put to provide some precision on the relationship that may exist between Open Regionalism and regional integration, and then it inquires of under what conditions regionalism can be a 'stepping stone' or 'building block' towards the improvement of multilateralism. The rapid economic growth in Asia provided a solid foundation for inter-firm networks and intra-regional trade and investment flows, with few institutional or government-led schemes. In the 1990s, Latin America, whose integration has often been characterized as 'policy driven', has also experienced a deepening of de facto integration, resulting in stronger intra-regional trade and investment linkages. Chapter II reviews briefly the impact of the recent economic crisis on production, trade and investment patterns for each region and identifies integration instruments that might be compatible with and conducive to policies to enhance the synergetic effects of de facto and policy-driven integration. 'deep' integration usually refers to an integration that deals with 'behind the border' issues, going further than 'shallow' integration that involves mainly the reduction of measures applied at the border. Chapter III analyzes the appropriate scope and nature of 'new' trade issues to be included in 'deep' integration of developing countries and assess whether the initiatives through regional agreements can be more effective than those undertaken at the multilateral level. The chapter elaborates on arguments, in favor of or against, potential dynamic benefits and costs that might be involved with regional cooperation, in areas such as, services, investment, infrastructure, trade finance, social and equity problems, small-and medium-size enterprises. Chapter IV analyzes the implication of the Uruguay Round commitments on the development process and major problems faced in their implementation. Based on this review, the chapter identifies the major areas of interests of developing countries for a new 'millennium Round'. In doing so, some new 'Conditionalities' and opportunities that the new round might introduce on regional agreements are considered.