In the thirty years since the invention of the CO2 gas laser, the major design issue has shifted from how to obtain the desired power level to how to achieve reliable operation. At the same time, the opening of many laser development facilities in the Former Soviet Union has allowed their achievements and design approaches to be understood and appreciated for the first time. Further, the industrial laser user community has identified a number of emerging applications at higher power levels (15-20 kW) than are attainable by most commercial devices. In High Power Lasers - Science and Engineering, the designers, developers and users of high-power gas laser systems discuss design approaches, methods of enhancing performance, new applications, and user requirements.