Schlingermann, BE, Lodge, CA, Gissane, C, and Rankin, PM. Effects of the Gaelic Athletic Association 15 on lower extremity injury incidence and neuromuscular functional outcomes in collegiate Gaelic games. J Strength Cond Res 32(7): 1993–2001, 2018—The purpose of this observational analytical cohort study was to assess the effectiveness of an injury prevention program (IPP)—Gaelic Athletic Association 15 (GAA15)—on the incidence of injury in collegiate Gaelic games. One hundred and thirty-one Gaelic games players (mean age 20.5 years ± SD 3.0) were used for analysis in this study. Participants completed preseason and postseason testing which involved performance of the Y-Balance Test. The GAA15 was used for the intervention group; coaches were instructed to implement the program before every training session and match throughout the collegiate Gaelic Athletic Association (GAA) season. The control group adopted their normal warm-up procedures for the season. The players' injuries were documented on a weekly basis by allied health care professionals working with the teams using an online database system. Results showed significant improvements in composite Y-Balance scores in favor of the intervention group (adjusted mean difference Right: 1.8 % normalized mean reach distance (%NMRD) [p = 0.007]/Left: 2.3 %NMRD [p = 0.001]). Injury rates in the intervention group (2.62 injuries per 1,000 hours) were reduced by 66% (p = 0.001) in comparison with an age-matched control group (7.62 per 1,000 hour). Training injuries, hamstring injuries, noncontact injuries, and severe injuries were also reduced as a result of the implementation of the GAA15 (injury rate ratio: 0.20, 0.59, 0.39, and 0.45, respectively). Implementation of an IPP such as the GAA15 can reduce the risk of injury in Gaelic games and influence players' neuromuscular performance assessed through the Y-Balance Test.