This paper summarizes the background, methodology and findings of initial efforts to improve our approach to training and assessing high-performance skills. High performance skills are those that require accurate and precise perceptual - motor coordination to achieve desired levels of expertise. We review and integrate key areas of knowledge related to skill acquisition and expertise, address strategies for teaching and assessing complex skills, and examine the use of technologies that enable precise recording of trainee performance. Instructional strategies are discussed that are designed to accelerate complex skill development, based upon learning principles and enhanced performance feedback. Our emphasis is on teaching the "warrior" skills needed for military serviceman now engaged in very different and challenging war-fighting tasks. Developments in simulation training technologies, with performance monitoring capabilities, provide a means for studying and improving high performance skills. The US Army's Engagement Skills Trainer (EST) was designed to teach basic and advanced marksmanship skills, and can be used to monitor performance progress from novice to expert. In this paper, the EST was used as a test bed to explore possible training enhancements and performance assessment metrics for military rifle marksmanship training. Our study of marksmanship skill benefited from the emergence of precise instrumentation for digital recording of trainee performance. We used motion capture technology to define and to measure proper rifle shooting postural profiles associated with different levels of marksmanship expertise. Motion capture allowed us to model various levels of expertise, ranging from novice to expert, as a means to define skill differences. While results reported here are promising, further research and development in motion capture is needed in order to realize the full potential for the practical application of shooting profiles in the determination of skill levels and analysis of learner deficiencies during simulation training.