This article presents an overview of a contemporary research protocol conducted at the Marine Corps Weapons Training Battalion, Quantico, VA. The study was a comprehensive collaborative research initiative that evaluated a variety of environmental, auditory, and vestibular factors among Marines enrolled in the Breacher Training Course. The length of each course is 2 weeks and involves multiple exposures to blast overpressure and physical shock from ingress strategies used during the training. Observational data were collected pretraining, during training, and posttraining between September and June 2007. There was no change in the way the Marines conducted their training, and all data were collected based on the actual training scenario. The primary objective of this research protocol was to determine if Marines in the Breacher Training Course were at risk of injury during standard training practices. The principal conclusions were that hearing loss was statistically and clinically significant whereas the vestibular findings were overall unremarkable.