Ducharme, SW, Wu, WFW, Lim, K, Porter, JM, and Geraldo, F. Standing long jump performance with an external focus of attention is improved as a result of a more effective projection angle. J Strength Cond Res 30(1): 276–281, 2016—Investigators have recently demonstrated that standing long jump performance is enhanced when participants focus their attention externally instead of their leg action but found no differences when examining peak force. The purpose of this study was to examine kinetic and kinematic properties associated with the standing long jump that may explain disparities between an internal and external focus of attention. It was hypothesized that the external focus condition would exhibit greater impulse values and a more optimal projection angle (45°) than the internal condition. Twenty-one participants each performed 5 total jumps: 1 baseline jump, in which no focus instructions were given, followed by 4 remaining jumps in which either internal or external focus instructions were introduced in a counter-balanced manner. Analysis of variance revealed that the external condition jumped significantly farther than the internal and baseline conditions. Analyses of kinetic measures (i.e., peak force and impulse) revealed no significant differences among conditions. However, there was a significant difference between the internal and baseline conditions compared with the external condition with respect to projection angle. Specifically, participants in the external focus condition exhibited an average projection angle of 45.7°, compared with the internal (49.5°) and baseline (49.0°) conditions. Therefore, the observed difference in jump distance among conditions can be explained by the external condition producing a more optimal projection angle. The results of this study partially support the constrained action hypothesis.