The paper is concerned with the problems associated with matching the output of a large nuclear-electric power source to the requirements of contact ion thrusters. The factors that influence the design requirements and the technical approach to power conditioning, switching, and control (PCSC) subsystems are discussed. Thruster requirements, power source characteristics, and environmental constraints are analyzed from the standpoint of their relationships to power conditioning. In addition, the results of the development of a breadboard PCSC unit at a 30-kw power level are described. This work gives an insight into the problems and the possible solutions that will result in the realization of power conditioning equipment whose specific weight, efficiency, and reliability are compatible with requirements of large scale nuclear-electric rockets of the future. In particular, one of the most promising experimental results is a 30-kw breadboard whose components exhibit a total weight of 3.2 lb/ kw. The results of a design study for a 300-kw system show that it is feasible to build a PCSC system weighing 9.1 Ib/kw input power including radiators and shadow shielding with a power efficiency of 93%.