The utilization of scaled models in the development of spacecraft thermal control systems is discussed. The criteria necessary to establish thermal similitude are developed as well as techniques for designing scaled thermal models. The application of thermal similitude criteria in experimental programs designed to verify the similitude criteria is reviewed. Several research programs which have applied thermal scale modeling to a radiation-conduction heat transfer system (unmanned spacecraft) and to a radiation-conduction-convection heat transfer system (manned spacecraft) are reviewed and evaluated. Recommendations as to the utilization of thermally scaled models are made, along with a discussion of the limitations on the use of such models. Finally, recommendations are made for further research.