AMTESS is the Army's attempt to develop an operational model and framework for acquiring modularized, generic simulation systems for maintenance training. More broadly, the AMTESS program is designed to lead toward a proven, systematized, institutionalized approach to task analysis, training requirements analysis, and fidelity analysis in support of training device acquisition. It is also designed to produce a model hardware configuration which includes a common two-dimensional display subsystem and a unique three dimensional hardware subsystem. Two prototype versions of the hardware model which vary along a number of significant dimensions (e.g., passive vs interactive use of video) are currently being evaluated for their transfer of training effectiveness at Aberdeen Proving Ground, Maryland. Transfer of training Is being assessed on operational equipment using specially modified versions of current performance tests, versions designed to provide a rich, detailed data based. The data base will support assessments of overall prototype effectiveness as well as preliminary assessments of the effectiveness of specific prototype features. The results of these efforts will support initial implementation of AMTESS and at the same time will contribute towards a longer range objective of developing an operational model of device acquisition. In this paper, the AMTESS prototypes will be described, along with plans and procedures for their evaluations.