Transitioning from high school to college can be a difficult experience; freshmen must adapt to life away from home, new responsibilities, and higher academic demands. For collegiate athletes, this transition also requires adjusting to more rigorous training and greater performance pressures. Together, these stressors may negatively impact health-related quality of life (HRQoL) among freshmen collegiate athletes. PURPOSE: To examine changes in HRQoL over a competitive season among freshmen and senior collegiate athletes. METHODS: 69 freshmen (age=18.2±0.47, male=56) and 23 senior (age=21.4±0.49, male=14) collegiate athletes at a large, Division I university completed the Short Form 12v2.0 Acute Recall (SF-12) prior to the start of the competitive season (PRE) and within 1 month following the end of the competitive season (POST). Participants included athletes who did not sustain an injury during the season or 6 months prior to PRE competing in football (freshman=36, senior=12), soccer (freshman=16, senior=3), and cross country (freshman=17, senior=8) over the 2013-2014 or 2014-2015 seasons. Raw scores were converted to norm-based scores via a linear z-score transformation. Changes (median (IQR)) in PRE to POST Mental Composite Score (MCS) and Physical Composite Score (PCS) were analyzed using Wilcoxon signed-rank tests. RESULTS: MCS significantly decreased (p<0.001) pre- to post-season among freshmen collegiate athletes (PRE=57.06 (54.79, 59.43), POST=54.67 (48.93, 57.06)). This decrease was observed in both males and females (p<0.001 and p=0.027, respectively). There was no change (p=0.341) in PCS among freshmen. Among senior collegiate athletes, MCS (PRE=55.34 (54.22, 58.26), POST=54.20 (49.50, 58.10)) and PCS (PRE=57.47 (54.39, 57.84), POST=56.71 (55.34, 58.40)) did not change significantly pre- to post-season (p=0.487 and p=0.889, respectively). CONCLUSION: Among freshmen collegiate athletes, mental aspects of HRQoL decreased over the course of the competitive season. Transitioning from high school to collegiate academics and athletics may produce high levels of psychological stress that can negatively impact HRQoL. University athletic programs should consider offering stress-management and counseling services to help incoming freshmen athletes adjust to college life.