Borderlands are often seen as zones of instability, uncertainty, marginality, and danger. Yet, they increasingly attract the attention of ethnographers as a unique lens through which to view the intersections of the national, transnational, and global forces that shape the securities and insecurities of our globalizing age. The contributors to this volume examine how different kinds of (in)security manifest and interconnect at state borders, encompassing the personal and the political, the social and the economic, in ways that reinforce or undermine the identities of those whose lives these borders frame. Drawing upon case studies from the Southern Cone, the U.S.-Mexico border, and borders in Greece, Ireland, and southeast Asia, the authors show that borders raise questions of security not just for those who live and cross them, including ethnographers, but also for the sustainability of the physical environments and wildlife disturbed by the passage, movement, and containment borders generate.