Physical performance tests (PPTs) have great allure to sports medicine professionals, coaches, and athletes because they are inexpensive, easy to perform in a variety of settings, and reportedly can be used as outcome measures to determine patient progress and readiness for return to sport as well as prognostic variables to predict injury or performance. However, there has been no evidence-based summary of literature with regard to the clinical utility of physical performance tests in athletes and most studies examining the clinical utility of PPTs are of small sample size or performed in limited populations. In addition, there are very few prospective studies examining the predictive ability of PPTs in athletes with lower extremity injuries. This dissertation encompasses 2 systematic reviews highlighting the absolute dearth of evidence in existence, the introduction of some novel PPTs and the establishment of their reliability, and a large, pragmatic, prospective study examining the ability of PPTs to predict lower extremity injury in collegiate athletes. The most notable findings of the prospective study are first, that PPTs fall cleanly into 5 constructs: stability, active motion, motor control, power, and flexibility. Next, the constructs of hip stability and active motion predicted injury. Third, the construct of motor control predicted overuse injury. Finally, the constructs of hip stability, active motion, and motor control appear to modify the relationship between injury and prior injury. Finally, the constructs represented by PPTs seem to be more powerful predictors of injury than the previously established predictors of age, body mass index, gender, and excessive flexibility when examined in a multivariate model.