Humankind's interest in the measurement of human physical strength probably dates to the first humans. At that time, life was truly a struggle in which the fittest survived. To a great extent, fittest meant strongest. It is perhaps ironic that in a modern civilized world, children still emphasize the relative importance of physical size and strength in determining the status hierarchy within a group. It is equally ironic that current interest in human physical strength comes from 1970s-1980s vintage research which demonstrated that persons with adequate physical strength were less likely to be injured on physically demanding jobs. Survival in many modern workplaces may still be a case of survival of the strongest. There is, however, a flip side to this issue. If persons with limited strength are likely to be injured on "hard" jobs, what we know about physical strength can be applied to job design so that "hard" jobs are changed into jobs the are within the physical strength capability of most people. Thus, since human physical strength is important, it is necessary' to find ways to quantify it through testing. This chapter is about human physical strength testing. Its purpose is not to recommend any particular type of testing, but rather to describe the types of testing that are available, and the uses to which strength testing has been put. It is up to individual users of the strength testing to decide which testing technique is the most appropriate for his or her particular application. This chapter discusses four types of strength testing: isometric, isoinertial, psychophysical, and isokinetic.