ad-spectrum radios were impractical (see Viterbi [1,2]). However, in commercial radios, inter- ference typically comes from other similar radios that are part of an over- all system, and these, unlike enemy jammers, can be controlled. Moreover, the criterion for capacity in many commercial systems is not the number of users per unit bandwidth but, more appropriately, the number of users in a large area. Since the first publication of Spread Spectrum Communications in 1985, a great deal of interest has been shown in spread-spectrum radios for com- mercial applications and has led to many significant developments. This chap- ter discusses some of the primary reasons for that interest and presents an overview of commercial spread-spectrum applications. Cooper and Nettleton [3], in 1978, were the first to recognize that digital spread-spectrum radios had a potentially higher capacity for mobile radio applications than the FM analog radios used at that time. Viterbi's paper on fast frequency hopping [4] was soon followed by the work of Goodman, Henry, and Prabu [5], while Turin [6] examined the use of these radios to overcome multipath for urban digital radios. These researchers were ahead of their time, since neither the technology required to provide low-cost implementations of their ideas nor a market demand for high-capacity mobile radios then existed. Viterbi's [7] consideration of a multiple-access satellite system for mobile users may have been a precursor of the Qualcomm systems in operation Key Events in the Commercial Market today. Indeed, the earliest commercial applications of spread-spectrum radios were for satellite communications with the small earth terminals used by Equitorial, a company founded by Professor Edwin Parker of Stanford University. The first widespread commercial application of spread-spectrum technology was in Equitorial's C-band receive-only small satellite earth stations [8, 9, 10]. In this application, each broadcast satel- lite channel required many receive-only earth stations, const