1.1 Increasing attention is being given to measuring trainee performance in synthetic training devices, as evidenced by the recent Air Force, NTDC, and NASA-sponsored efforts in this area cited in the bibliography. A fair summary of well-informed opinions in this area would be: a) Such measurement can be most useful (see par 2). b) Subjective measures, such as the traditional instructor ratings, do not meet the current requirements for reliable, valid, and practical measurement. c) Synthetic training equipment, especially of the digital variety, makes feasible the achievement of needed measures more expeditiously than in operational equipment. 1.2 This report intends to acquaint the non-technical reader with the potentialities and limitations of measuring trainee performance in synthetic training devices, and outline the steps needed to achieve these measures. As an introduction, the report intends to be limited in depth; for those desiring to explore the subject in greater depth, publications cited in the Bibliography should be consulted. Much of the information cited herein is derived from the reports listed in the Bibliography (par. 10); the report by Smode et al. was especially useful.