From the intersection of citizenship, critical migration studies, and science and technology studies (STS), this book examines, across the various case studies, configurations between technologies, infrastructures and citizenship that may constrain acts of citizenship in migration and border regimes; constitute contestation and participation over citizenship; or enable and shape alternative acts of citizenship in migration and border regimes. Technologies and infrastructures on the border are designed to position migrants in multiple and potentially contradictory forms; migrants crossing the border, in their turn, may choose to challenge and repurpose those technologies and infrastructures to match their interests. By elaborating on the notion of 'material citizenship politics', the contributors provide a detailed analysis of socio-material practices on the border that moves beyond portraying migrants as mere victims of border technologies and migration infrastructures and anchors critique on the inside of those practices. The chapters in this volume hope to contribute to setting the research agenda and to stimulate further research along these lines revisiting the (in)visibilities of migrant subjects along technologies and infrastructures. As the current pandemic unfolds, exposing societal vulnerabilities, this book highlights the need to critically reflect on the establishment of existing technologies and infrastructures in order to examine to what extent those affect and shape migrant subjects in particular, but may also be extended and used on wider populations after being tested and normalized on vulnerable subjects. This book will be of interest to a broad readership across the social sciences, including scholars working in Critical Migration and Border Studies, Citizenship Studies, Critical Security Studies, and Science and Technology Studies. The chapters in this book were originally published in the journal  Citizenship Studies.