This Ph.D. thesis aims to challenge stereotypes and obvious facts concerning the increasing integration of output and labor markets by quantifying the economic implications of migration and trade for the destination countries as well as their redistributive effects on the countries of origin through information transmission and international trade. From a methodological point of view, this thesis interlinks new trade theory and international migration. The first two chapters quantify the welfare resulting from an expansion of product varieties available to consumers (named the market size effect). The breakdown of national boundaries and factor mobility lead consumers to enter in an integrated global consumption market where then can better...