Despite evolutionary changes in protective equipment, head injury remains common in football. We investigated concussion in football and associated epidemiologic issues such as 1) incidence of injury, 2) common signs and symptoms, and 3) patterns in making return-to-play decisions. We received 242 of 392 surveys (62%) that were sent to high school and collegiate certified athletic trainers at the beginning of three football seasons. Of the 17,549 football players represented, 888 (5.1%) sustained at least one concussion, and 131 (14.7% of the 888) sustained a second injury during the same season. The greatest incidence of concussion was found at the high school (5.6%) and collegiate division III (5.5%) levels, suggesting that there is an association between level of play and the proportion of players injured. Players who sustained one concussion in a season were three times more likely to sustain a second concussion in the same season compared with uninjured players. Contact with artificial turf appears to be associated with a more serious concussion than contact with natural grass. Only 8.9% of all injuries involved loss of consciousness, while 86% involved a headache. Overall, 30.8% of all players sustaining a concussion returned to participation on the same day of injury.