It is not surprising that HCI researchers are attracted to the role of technology in global processes as many of us already live inherently transnational lives. While the notion of global connectedness is hardly new, the issues that confront us are more than specific concerns for remote migration, distributed work, or developing nations. Rather, we argue that transnational HCI is a contemporary condition of the design and use of technological systems, both at home and abroad. This special issue of Human-Computer Interaction is dedicated to exploring how and why a transnational lens matters to the study, design, and development of computational systems. We consider this theoretical perspective in terms of both present technology use to construct and manage transnational relations and processes, and the possibilities such a lens opens for future research and design. The papers in this issue contribute to the field of HCI by bringing the principles developed in anthropology, sociology, and elsewhere to bear on the conversation in HCI, retooling them for our present context, while preserving the richness of their methodological orientation.