In recent years, awareness of infrastructures has been building to a remarkable degree in virtually every area. The information infrastructure which subtends the revolutionary new forms of sociability, science, scholarship and business is one example. A second is the state of roads, bridges, dams, and other large, expensive, long-term investments as our national and international infrastructures fall into disrepair. A third is the energy infrastructures, both old (fossil fuels) and new (renewables), that subtend the world economy. A few centers of important scholarship on infrastructures have emerged, such as large technical systems theory (history of technology), urban infrastructures (urban planning, geography), and information infrastructures (information studies, computer-supported cooperative work). Yet too much of this work has been siloed, focusing only on a particular system or scale, and with few exceptions it has remained sequestered within some of the smaller academic fields. Finally, remarkably little work has been done on the comparative study of infrastructures: taking lessons from one field and modifying it for another. Publications in Infrastructures seek to engage with broad theories of infrastructure and foreground the usually hidden aspects of infrastructures, be they material, informational, or structural.