Unauthorized immigration is on the rise again in the EU. Although precise estimates are hard to come by, proximity to nations in turmoil and the promise of a better life have drawn hundreds of thousands of irregular migrants to the EU in 2014-2015. Further complicating the ongoing challenge is the confounding flow of humanitarian migrants, who are fleeing not for a job but for their lives. Those who flee for better economic conditions are irregular migrants, not humanitarian migrants, but the lines between the two are often blurred. This policy brief surveys the state of irregular immigration to the EU and draws on lessons from the U.S. experience. It focuses on economic aspects of unauthorized immigration. There are economic benefits to receiving countries as well as to unauthorized migrants themselves, but those benefits require that migrants are able to access the labor market and that prices and wages are flexible. Meanwhile, mitigating fiscal costs requires limiting access to public assistance programs for newcomers. Successfully addressing irregular migration is likely to require considerable coordination and cost-sharing among EU member states.