A nearly two decades of research and development, and several recent and ongoing successful tests in space, electric propulsion systems are emerging which are capable of fulfilling the secondary propulsion requirements of initial station acquisition, stationkeeping, attitude control, and modest repositioning, as well as providing primary propulsion for a wide range of interesting missions. Further, system reliability has now advanced sufficiently to project electric propulsion to the threshold of several flights, where it will be an integral part of functioning spacecraft. Many excellent reviews of the historical development and status of electric propulsion have appeared in the literature." The purpose of this paper is to provide the spacecraft designer with sufficient information regarding the recent progress and present capability of the several types of electric propulsion systems to enable him to optimize his selection for a particular mission. To this end, each of four major classes of electric thruster (electrothermal, plasma, colloid, and ion) is briefly described and the distinct programs in each class reviewed. The emphasis is on performance capability, development status, program goals, and technology improvement. Adequate references are provided for a more detailed examination of each thruster program.