Rectifying the fact that little criminological attention has been paid to the notion that the security of flows increasingly embodies concerns at the heart of contemporary policing practices, this book makes a significant contribution to knowledge about the policing and security governance of flows. The book focuses on how the growing centrality of flows affects both contemporary 'risks' and the policing organisations in charge of managing them. The contributors analyse flows such as event security; border controls and migration; the movement of animal parts; security-related intelligence; and organisational flows. The emerging criminology of these, as well as flows of money, information and numerous commodities, from pharmaceuticals to minerals or malicious software, is leading to critical advances in the understanding of the changing harm landscapes and the practices that have developed to manage them. Taken as a whole, the book opens up the conversation, and encourages the invention of new conceptual, theoretical and methodological tools to help criminology tackle and better understand the mobile world in which we live. This book was originally published as a special issue of Global Crime.