A concussion is "a complex pathophysiological process affecting the brain, induced by biomechanical forces" (McCrory et al., 2013, p. 250). Although this is a good theoretical definition, it lacks practical utility and does not reflect the evolving definition of this type of injury. A more contemporary approach would extend the above definition as follows: a complex pathophysiological process affecting the brain, induced by biomechanical forces, which manifests in different symptoms, impairment, clinical profiles, and recovery trajectories that are influenced by risk or modifying factors. Concussions affect millions of athletes each year, with recent estimates suggesting as many as four million sport-related concussions have occurred in the United States alone (Langlois, Rutland-Brown, & Wald, 2006). Although concussions typically resolve within 2 to 3 weeks in adults and 3 to 4 weeks in children, some athletes may experience symptoms and cognitive impairment for months or longer (McCrory et al., 2017). The Centers for Disease Control (CDC), which declared concussion a major health issue in the United States, has estimated the economic impact of concussions on medical expenses to be up to $17 billion annually in the United States alone. Recent lawsuits involving the purported short-and long-term effects of concussions among athletes from the National Collegiate Athletic Association, United States Soccer, and the National Football League have further highlighted the economic and societal importance of this injury. Despite the heightened contemporary attention, however, concussions were not always viewed as a serious injury.As recently as the early 2000s, concussions were described using innocuous sounding terminology, such as "bell ringer," "ding," and "knock." If an athlete did not experience a loss of consciousnesswhich is now known to occur in no more than 10% of concussions (Guskiewicz, Weaver, Padua, & Garrett, 2000)-he or she was allowed to continue to play. Even with loss of consciousness, many players returned to competition or practice the same day or soon after. In short, concussions were not perceived as a big deal in sport and were rarely discussed or even acknowledged by many researchers and practitioners in the medical community. Fast-forward to today, and the pendulum has swung in the other direction: Many parents fear that every collision or ball to the head will yield a concussion that may lead to long-term or even permanent effects. In fact, in a recent Harris Poll of more than 2,000 parents of athletes, one in four reported that they thought a concussion would change a person' s life forever, while 72% believed that damage to the brain from a concussion is permanent (Collins, 2015). In extreme examples, young athletes with a concussion are kept out of school for months and some clinicians even prescribe complete rest (i.e., cocoon therapy), resulting in social isolation and an exacerbation of symptoms (Collins et al., 2016).Today, concussions are ubiquitous, with considerable attention from the ...