It has been just over twenty-five years since “transnationalism” was born – as a perspective, a concept, and a research project. It fit easily into the globalization talk of the late 20th century and seemed obvious once revealed. Transnationalism means many things to many people, from crossing physical borders to crossing intellectual ones. Many use transnationalism to argue that we cannot do history in one country. For historians, transnationalism has become both a historiographic perspective and a search for and analysis of transnationals/isms past, be they in the form of movement of ideas, goods, or people. This book aims to question this “transnational moment” in particular as it relates to human mobility. Insofar as transnationalism has come to emphasize a somewhat heroic sense of individual opportunity, the difficulties of transnational activities have been lost from sight. While transnationalism arose as an understandably powerful antidote to the older sturm und drang of migration studies, it has perhaps led to an overly optimistic vision of migrant agency. Two criticisms may be raised. On the one hand, as has by now been amply shown, transnationalism is not a new phenomenon. On the other hand, as this book will explore, it is also not as easy as it looks. It is time to take a closer look at the metaphoric and real obstacles to transnational mobility. The Limits of Transnationalism thus explores a part of the story seldom told: the complications, the possible downsides, and the eventual failure of networks.