Int J Exerc Sci 2(1): S22, 2009. This is a novel descriptive study to characterize off-season, pre-season, and post-season bone and body composition measures in women collegiate athletes. PURPOSE: To quantify changes in women collegiate athletes' bone mineral content, bone mineral density (BMD), arm BMD, leg BMD, pelvis BMD, spine BMD, and body composition (i.e., total body mass, lean mass, fat mass, and percent body fat) within each sport through the seasonal periods, and among the sports at each seasonal period. METHODS: 67 women collegiate athletes from softball (n = 17), basketball (n = 10), volleyball (n = 7), swimming (n = 16), and track jumpers and sprinters (n = 17) were scanned using duel energy x-ray absorptiometry (DXA) at three seasonal periods: 1) before pre-season training defined as off-season (OFF), 2) at end of preseason training (PRE), and 3) after the competitive season (POST). Summary of RESULTS: Repeated measures ANOVA within-sport seasonal changes in Values are means ± standard deviations. *Significant difference between offseason and pre or post-season. ANOVA for differences by sports at the PRE/POST period showed results for both pelvis BMD and spine BMD as follows: softball = basketball = volleyball = track > swimmers. CONCLUSION: These data serve as sportspecific benchmarks for comparisons at in-season and off-season training periods among women collegiate athletes in various sports. They also serve to document changes in body composition and bone density with training, and may serve to guide coaches in the development of sport specific nutritional and strength and conditioning programs to optimize athletic performance.