This volume is a collection of papers that apply general equilibrium theory in order to obtain policy relevant insights on topical issues of international trade and migration. The first set of papers focuses on European integration, applying dynamic numerical general equilibrium methods to quantify the effects of geographic extension of the European Union, including the effects of Eastern enlargement of the EU on incumbent Western member countries. The second set of papers deals with the trade effects of WTO membership, with special focus on the so-called extensive country margin, where new international trading relationships are formed. The third set of papers focuses on immigration, offering a rigorous theoretical analysis of the so-called immigration surplus as well as an econometric estimation of the gains and pain that Germany has forgone by initially restricting immigration from new EU member countries after the EU's Eastern enlargement in 2004. And finally, the book contains a set of theoretical papers on the distributional effects of offshoring.