Two lines of research concerning the dimensionality of physical performance in occupational tasks are described. In the first, the physical requirements of tasks are analyzed as reflected in job analyses. In the second, the structure of physical abilities tests used to predict performance in physically demanding jobs is evaluated. Principal components analyses of both job analysis and test performance data suggest that the structure of physical abilities has three major components--strength, endurance, and movement quality. This structure appears to be independent of job type or level of incumbents' performance.