Over the last two decades of the world economy development, both the process of global/multilateral trade liberalization and the regional economic integration have intensified in parallel. Contemporary economists are unanimous in asserting a strong interdependence between the two processes. The voices are much less in accord as to the normative evaluation of this correlation. This paper will offer a detailed analysis of both the 'pessimist' and the 'optimist' arguments. The analysis will try to clarify whether the regional trading arrangements obstruct or facilitate the process of multilateral trade liberalization. The analysis takes heed to distinguish between earlier waves of regionalism in the world economy and the latest wave, which support the argument that new regionalism is relatively “benign” to outsiders and the multilateral trading system as the whole. Since the global trade liberalization is led primarily through the World Trade Organization (WTO), the analysis is particularly sensitive to the norms and principles of the General Agreement on Tariffs and Trade (GATT), i.e. the part played by the WTO as a key factor in establishing what influence the regional integration exerts upon the process of multilateral trade liberalization.