Parsonage, J, Webster, H, Keogh, JWL, Gosney, S, MacDonald, LA, and Minahan, C. Relationships among sprint-paddling performance, shoulder function, and upper-body strength, in female surfers. J Strength Cond Res XX(X): 000-000, 2025-The aim of this study was to establish the intrasession and intersession reliability of 2 water-based tests to determine sprint-paddling performance and the relationships of water-based sprint-paddling performance, upper-body strength, and shoulder function in female surfers. Ten female surfers (age = 30.0 ± 6.3 years, mass = 65.5 ± 8.7 kg, height = 170.0 ± 6.0 cm) completed 3 trials of an 8-s "tethered" and a 15-m "free" sprint-paddling test during 2 independent sessions. Dryland assessments included shoulder range of motion, shoulder isometric peak force (internal and external rotation at 90° abduction), and 1 repetition maximum pull-up. Reliability was assessed using intraclass correlation coefficient (ICC), coefficient of variation (%CV), and typical error (TE). Excellent intrasession (ICC = 0.97, CV% = 2.98, TE = 0.04) and intersession (ICC = 0.97, CV% = 3.11, TE = 0.04) reliability was established for average force during tethered paddling, with moderate intersession (ICC = 0.59, CV% = 9.74, TE = 0.21) reliability established in measures of peak force. The 15-m free sprint-paddling test demonstrated good-to-excellent intrasession (ICC = 0.76-0.94, CV% = 1.55-2.52, TE = 0.16-0.33) and moderate-to-good intersession reliability (ICC = 0.58-0.76, CV% = 2.58-3.32, TE = 0.21-0.37) across 5, 10, and 15 m. Significant inverse associations were found between shoulder external range of motion and average sprint-paddle force (r = -0.65 to -0.69, p < 0.05), and between the nondominant arm's external shoulder rotation strength at 90° and time to 5, 10, and 15 m (r = -0.63 to -0.65, p < 0.05). Maximal pull-up strength was not associated with either paddle assessment. This study demonstrates that tethered and free sprint-paddling tests are reliable methods of assessing sprint-paddling performance in female surfers and that assessments of shoulder function require further investigation with a larger sample of strength-trained surfers.