The Moving Target Screen, a performance-based functional assessment tool for adults older than 50 years, is designed to be used by exercise specialists to evaluate the 5 key aspects of fitness central to optimal aging: posture, flexibility, balance, endurance, and strength. The strength of evidence supporting each of the 15 tests that comprise the Moving Target Screen is described. The assessments require inexpensive, standard equipment used by physical and occupational therapists. The Moving Target Screen can be a powerful tool that provides a comprehensive picture of a person's function before disability and problems begin or progress. It is also useful in documenting functional changes.