This report contributes to the migrationpolicy debates in the Greater Mekong Sub-region (GMS) byproviding evidence of the impacts of migration; at the sametime, it outlines possible policy approaches to increasebenefits from migration. The study focuses primarily onThailand and Myanmar: the main labor receiving and sendingcountries, respectively, in the GMS. This report not onlypresents the recent migration trends and drivers in the GMSbut also addresses policy issues related to the economic andsocial impact of migration on countries both receiving andsending labor; it also addresses the issue of migrants'welfare including social services; and the role of migrationpolicy and institutions. The findings challenge severalexisting paradigms of developing country migration researchand may have broader transferability. Specifically, theproceeding analysis suggests: (a) demographic and incomedifferences among the GMS countries drive migration withinthe region, suggesting the rising prominence of South-Southmigration; (b) migration in the GMS tends to be long-term,contrasting the more temporary nature of migration from mostof the world's developing countries; and (c) economicfactors contribute to migration within the regionsignificantly more so than political factors.