Increasingly stringent demands are being placed on operators in many military systems due to recent advances in technology and rapid changes in the world order. In the modern military combat environment, operators require skill levels that are more varied and are of a higher order than in the past. Coupled with current fiscal constraints, this situation demands an optimization of training resources-a return on investment that results in an uncompromisingly high level of readiness at the lowest possible cost and in the shortest time. The purpose of this research was to advance understanding of effective training system design by investigating factors that may affect the success of training significantly in terms of performance improvement in the operational environment. To accomplish this goal, a comprehensive model of training effectiveness was first developed and used as a basis to specify testable hypotheses. A large-scale data collection effort to test portions of the model was then conducted with Navy recruits. Results indicated that several nontechnical trainee-related factors had a significant impact on training outcomes in this setting: self-efficacy, task-related attitudes, expectations for training, training fulfillment, and pretraining motivation. These results are discussed in terms of their implications for future research and for improving training system design.