This introduction to the special issue Irregular Migrants: Policy, Politics, Motives and Everyday Lives outlines the changing patterns of irregular migration at the end of the twentieth century and the start of the twenty-first century, explores the ways in which irregular migration has been analysed conceptually and empirically, highlights the contribution the volume as a whole makes to the literature in this domain and examines the key emergent themes from the papers in this volume. Finally, the paper concludes by suggesting gaps in our knowledge and areas for further research.