Abstract This chapter describes the development of low-cost wireless sensors for monitoring civil infrastructure systems. The historical development of wireless sensor hardware and software design is described in detail. The embedded data processing algorithms that allow wireless sensors to locally process raw structural response data are presented. To illustrate the utility of wireless structural monitoring systems, a variety of field studies are presented including instrumentation upon complex bridges and buildings. The chapter concludes with more recent work in integrating wireless sensors within feedback control systems for the seismic protection of civil structures.