Immobility is inextricably, albeit often invisibly, linked to our understandings of human mobility. Whenever we seek to understand the drivers or outcomes of migration, we are, in fact, asking why people don’t stay and what that means for them, their families and for affected societies. While academics, media, policy makers and the public typically focus on migration and displacement as they result at least partially from climate change, natural and man-made disasters, and other environmental stressors, a small but growing body of work highlights the importance of addressing and understanding those who do not leave such areas. This chapter compiles current knowledge on ‘trapped populations’, but also on various forms of immobility, including those who choose to stay. It identifies current evidence, trends and empirical and theoretical gaps; posits several future avenues of research; and addresses the political significance of immobility.