The classical ergonomics approach to workplace assessment includes consideration of the relevant task demands and characteristics of human capacity. In the case of the upper extremity, the primary exposure parameters measured often include force, posture, repetition, duration and environmental variables (i.e., vibration and temperature). Assessment is often best accomplished through direct measurement. The use of position, force and torque transducers, and electromyography electrodes provide the foundation for a direct measurement strategy that has been used to quantify these demands. The development and refinement of apparatus and approaches in our Research Center will be discussed, including specific laboratory and field applications. Similarly, methods for quantifying the typical capacity of the upper extremity, variations in capacity, and methods of relating capacity to performance requirements will be discussed.