Sport-related concussion (SRC) is a common mild traumatic brain injury among young, active individuals, affecting approximately 300,000 young American adults annually. In this review of the epidemiology of SRC, we describe the challenges in identifying concussion occurrence and review the studies describing concussion incidence in various sports. In high risk contact sports, American football, soccer (European football), hockey, lacrosse, and basketball athletes experience concussion unintentionally during the course of play. Among these, football concussion incidence is reviewed in greatest detail because it has the highest incidence among the contact sports, and some studies have shown long-term neurophysiologic and neurodegenerative outcomes. Mechanisms of injury differ significantly by sport and can be potential targets for concussion risk mitigation. Despite the apparent high incidence of SRC, risk factors determining initial concussion, recovery periods, recurrence, and long-term outcomes remain poorly understood and warrant further study exploring the influence of age, sex, genetics, and athletic factors.