The purpose of this study was to examine changes in body composition (BC) and physical performance tests (PT) resulting from a competitive season in soccer. Twenty-five male collegiate players (age = 19.9 ± 1.3 years; height = 177.6 ± 6.4 cm; body mass = 77.6 ± 8.6 kg, and percentage body fat = 12.8 ± 5.2%) were tested before (PRE) and after (POST) the 2003–2004 National Collegiate Athletic Association season. The following tests were performed: BC (anthropometric and dual energy x-ray absorptiometry measurements), vertical jump (VJ), 9.1-m (9 m) and 36.5-m (36 m) sprint, lower-body power (LP), total body power (TP), and cardiorespiratory endurance (O2max). Training was divided into soccer-specific training: field warm-up drills, practices, games, and additional conditioning sessions. A daily, unplanned, nonlinear periodization model was used to assign session volume and intensity for strength sessions (total repetitions ≤96 and workload was ≥80% of 1 repetition maximum). For the entire team, body mass significantly increased by 1.5 ± 0.4 kg from PRE to POST due to a significant increase in total lean tissue (0.9 ± 0.2 kg). Regionally, lean tissue mass significantly increased in the legs (0.4 ± 0.0 kg) and trunk (0.3 ± 0.1 kg). Physical performance variables were very similar for the entire team at PRE and POST; VJ (cm) = 61.9 ± 7.1 PRE vs. 63.3 ± 8.0 POST, 9.1-m (s) = 1.7 ± 0.1 PRE and POST, 36.5-m (s) = 5.0 ± 0.2 PRE and POST, predicted O2max (ml·kg·min−1)= 59.8 ± 3.3 PRE vs. 60.9 ± 3.4 POST. The only significant improvements across the season were for TP (17.3%) and for LP (10.7%). In conclusion, soccer athletes who begin a season with a high level of fitness can maintain, and in some cases improve, body composition and physical performance from before to after a competitive season. A correct combination of soccer-specific practices and strength and conditioning programs can maintain and develop physical performance, allowing a soccer athlete to perform optimally throughout pre-, in-, and postseason play.