This book is the latest step in the long-standing dialogue between two academic fields: transnational studies and diaspora studies. These share a common initial intent: the will to place migrants' experience at the core of migration studies, rather than on the integration of migrants into the new host society or the development of origin societies. However, the two endeavors also differ. Scholars of diaspora have focused on the processes through which migrants maintain a shared identity despite their dispersion and its consequences for integration and state politics. In contrast, transnationalists focus on micro-level practices and networks forged by migrants across state borders without necessarily presuming a shared sense of belonging. Recently, the two fields of study have followed converging paths. Works on diasporas have increasingly incorporated micro-level activities in their analysis while, conversely, research on transnationalism has paid growing attention to the importance of macro-level dynamics and actors such as states. In 1999, Robin Cohen and Steven Vertovec's book and in particular their landmark "Introduction" heralded this convergence. Since then, diasporic groups are commonly perceived as a specific category of transnational formation. Admittedly, diasporas differ from other transnational communities, owing to an enduring group consciousness forged through cross-borders ties and practices. Although Diaspora and Transnationalism endorses this view, it also reveals new perspectives on the scholarship not only in the two related fields, but others as well. Indeed, since the early 2000s, the concepts of diaspora and (to a lesser extent) transnationalism have permeated the vocabulary of policy makers. The growing number of diasporic policies formulated by states and intended to attract the economic favor of their expatriate groups has led some academics to revisit common assumptions and theories about the making of transnational and diaspora groups. In consequence, new theoretical stances have emerged. Diaspora and Transnationalism reflects the current re-composition of the academic debate. The book is divided into three sections that explore the theoretical, conceptual, and methodological frameworks of the two approaches. This opus is an effort to shed new light on diaspora and transnationalism by redrawing the margins that separate and juxtapose them. The project that underpins this work is one of redefinition, of pointing to the content of the concepts at issue and exploring possible combinations. At first sight, no common ground emerges from this collection of papers. In many regards, this book appears as a series of monologues on diaspora, transnationalism, and sometimes (but not always) their relationships. The aim of the book is not to weave together an overarching theory. Nevertheless, its merit is to provide a panoramic view of the variety of themes, perspectives, and methods through which the relationship of diaspora and transnationalism is currently addressed by students of migration. In the first place, the book illustrates the convergence between the two fields, which is partially related to the growing politicization of the notion of diaspora. In an attempt to provide a theoretical justification for this convergence, Thomas Faist argues that diaspora and transnational studies share the same epistemological terrain, one that lies between methodological nationalism and globalization studies. In addition, several other articles (by Valentina Mazzucato, Koen Jonkers, Kathrin Kissau, Uwe Hunger, Laura Morales, and Laia Jorba) show how recent methodological innovations have provided common methodological tools for the study of diasporas and transnational phenomena. But, in the second place, Diaspora and Transnationalism reflects persistent past and recent academic quibbles. Several contributions make the case that contemporary diaspora formations are an outcome of state efforts to engage with their nationals living abroad. In contrast, transnationalism appears as a grassroots process that escapes from state control (see Rainer Bauböck). In this respect, the book is strongly marked by a recent neorealist turn in migration studies (that will be discussed later; it illustrates the current re-evaluation of the role of the state in the formation of cross-border social entities. In this essay, I will successively present the two opposite trends that characterize contemporary debate...