Abstract: This paper proposes the hypothesis that multilateralism and regionalism are complementary, and that regional income convergence is likely with a like minded and committed regionalism that often has links geographically and culturally. The association between international trade, income per capita, and regional income convergence in founder members of ASEAN and SAARC, is explored by applying the Lumsdaine, and Papell approach. The causal relationships between the above variables are also studied in respective trade blocs by using Granger causality tests. The conclusion is that global reforms have had a greater impact on increasing trade for both trade blocs and induced convergence only in ASEAN-5 countries. The experience of ASEAN countries shows a two-way causal relationship between the flow from trade to regional income convergence, and vice versa. There is no evidence in SAARC countries for income convergence and causality.