Thirty-five million Europeans immigrated to the United States from 1840 to 1920. Their successful integration provides much hope that the United States and Europe can successfully meet the challenges presented by the modern large-scale migrations of Mexicans to the United States and Muslims to Europe . Such success, however, is not inevitable. Each of these immigrant groups presents numerous integration challenges. Some of the challenges echo issues that arose a century ago in the great European migrations to the United States. Others may be considered new, however, such as those that arise from certain developments in technology, globalization, and the welfare state. For example, how does the availability of the internet and cable television, which make it easier for migrants to remain informed about personal and public developments in their home countries, impact integration? Does the provision of welfare benefits to migrants impede successful integration? And what are the immigration and integration implications of the possible evolution of the nation-state to what has been termed the “market-state”? This article discusses these and similar questions relevant to immigrant integration today, while drawing lessons from past successes and suggesting areas for future research.