The purpose of this dissertation was to explore the interrelationships of several important fitness characteristics in Division 1 athletes. Sport performance magnitude is the summation of an individual athlete’s technical, psychological, and fitness characteristics. Athletes who excel in any or all characteristics perform better in their chosen sports. General fitness characteristics that are important to almost all sports include strength, power, vertical jump height, shortdistance sprinting ability, muscularity, and body fat percentage. These variables have been shown in previous research to independently affect athletic performance outcomes, but their relationships to one another are less clear. Eighty Division I athletes from 4 sports were examined in a variety of fitness characteristics as part of a continuous athlete monitoring program. Data on strength, power, vertical jump height, short-distance sprinting speed, muscularity, and body fat percentage were collected and analyzed. Analysis revealed several important relationships. Firstly, strength is highly related to muscularity, with lean body mass as one of the most important determinants of strength. Secondly, athletes who can produce high relative (scaled per body mass) forces and powers tend to be considerably higher jumpers and much faster sprinters. Lastly, leaner athletes out-perform less lean athletes in almost every metric, especially relative strength and power, vertical jumping ability, and sprinting ability.