Training effectiveness should be the driving force behind the procurement and use of training systems. However, there are major difficulties to overcome in the evaluation of aircraft training systems effectiveness. The main difficulty stems from the complexity of the issue, which results in a lack of clear operational definitions. The Naval Training Equipment Center has initiated a research program in Training Effectiveness Evaluation (TEE), an initial part of which is to develop a model of the TEE process. The main objective of the initial phase of the program is to define the elements needed in TEE and to specify the interrelationships among critical elements. Another objective is to foster better communications within the training and operational community.