International migration has been described as one of the defining issues of the twenty-first century (Betts, 2015). The movement of people across borders has profound social, cultural, economic and geopolitical ramifications. While a vast literature explores the complex nature, scope and significance of migratory flows, surprisingly little attention has been given to one of the most prominent responses by governments to human mobility: the practice of immigration detention. This volume is grounded in the conviction that immigration detention – often hidden from public view – requires scholarly attention equal to that given to the more visible and better known dimensions of international migration. The contributions to this volume together offer a timely intervention in a developing field of inquiry, providing much needed scrutiny of the ideologies, policies and practices that gird the troubling, unparalleled and seemingly unbridled growth of immigration detention. While previous scholarship has examined the growth in detention at the macro level, a distinctive characteristic of this volume is its attention to micro-level processes. Through careful consideration of the intimate economies of immigration detention – that is, the complex systems of micro and macro relationships that enmesh in the realisation of detention and lived experiences of being detained – the contributors collectively prise open the concealed worlds of immigration detention, shedding necessary light on the costs and implications of an increasingly prevalent form of human confinement.