There is general agreement among instructional designers that training people to maintain complex systems has unique characteristics not found in other training endeavors. These unique characteristics stem from the kind of cognitive and psychophysical tasks which must be performed by the system maintainer. This paper discusses the uniqueness required of maintenance training systems and sets out a model for designing such systems. Examples from basic and advanced maintenance training systems are presented with a discussion of how and why particular instructional strategies were selected. Alternative strategy selection techniques are discussed. A review of current simulation techniques for training maintenance tasks is presented in the context of general design considerations for maintenance training. Computer-based systems are compared along dimensions of cost, reliability, modifiability, hands-on capability, safety, and student performance data. A concurrent problem in maintenance training is the determination of whether a training system is, in fact, functioning efficiently and effectively. Efficiency and effectiveness are defined and a model for measuring each is proposed. A section of the paper addresses the economic issues in the evaluation of training.