The use of simulator training for operators of the generation/transmission/distribution grid has increased dramatically since the introduction of the first operator training simulator in 1977. Simulator training in power systems, as in other industries, provides an efficient method of exposing the operator to various emergency conditions. These emergeacy situations occur rarely in real life and the history of black-outs and brown-outs suggests that on-tQe-job and other methods of training are not very effective when confronted with such conditions. The development of operator training simulators, however, depended on the availability of economical computational hardware. In addition, models and algorithms to simulate large power systems in real time required significant innovation. Although better models and algorithms continue to be developed, the emphasis on research today is not on still higher fidelity but on features that enhance training. This paper reviews briefly the state of the art of operator training simulators for terrestrial power systems.