Individuals jump higher when they adopt an external focus of attention, relative to an internal focus or no focus of attention (G. Wulf, T. Zachry, C. Granados, & J. S. Dufek, 2007). In the present study, the authors determined the underlying cause of this effect. Participants performed a vertical jump-and-reach task for (a) an external focus condition (i.e., participants focused on the rungs of a Vertec [Perform Better, Cranston, RI] measurement device that they touched) and (b) an internal focus condition (i.e., participants focused on the finger with which they touched the rungs). Participants' jump height, center-of-mass displacement, jump impulse, and lower extremity joint moments were greater with an external focus compared with an internal focus. These results suggest that participants jump higher by producing greater forces when they adopt an external focus. This finding adds to evidence that an external focus facilitates the production of effective and efficient movement patterns.