This observational cohort study will enroll 4,800 cadets at the three large U.S. military academies; approximately 50% of those enrolled will be women. Only incoming cadets at the U.S. Naval, Air Force, or Military Academies will be able to participate. Each study participant will undergo a baseline assessment that will include measurement of neuromuscular risk factors using motion analysis, strength testing, and standardized assessment of poor jump-landing technique using the Landing Error Score System (LESS). All participants will be followed for up to 4 years. ACL injuries will be prospectively identified; an injury questionnaire is administered to participants who sustain an ACL injury while they are cadets. Otherwise, there is no further contact.