CO lasers are attracting increasing attention as the result of demonstrated advantages in power conversion and volumetric efficiency, and projections of favorable atmospheric propagation characteristics. A high energy pulsed electric discharge laser has demonstrated efficiencies in excess of 60%, and a small (~1 liter) supersonic CO EDL has produced over 100 kW under quasi-cw conditions (~2 milliseconds). Further improvements in performance are anticipated for optimized devices. Balanced against these advantages are a number of technological problems which must be addressed before practical devices can be realized. Of particular significance are the problems associated with obtaining diffraction limited performance. Beam quality may be degraded by many factors, e. g. , flow induced medium inhomogeneities, non-uniform heat addition, boundary layer effects, turbulent fluctuations, and component limitations. The effects are particularly pronounced for CO EDL's because of the high density of the active medium, and devices must be designed to minimize or compensate for these disturbances. This paper briefly reviews the status of CO EDL technology and the considerations which must be taken into account in the design of this class of device.