Researchers used biomechanical sensors to investigate exposure to head impacts during practice sessions and games in 9- to 11-year-olds engaged in a youth football program. The object of the study was to identify specific football drills that result in high-magnitude head impacts (measured as head accelerations greater than 40g). Data were collected throughout an entire youth football season consisting of 55 practice sessions and 10 games. In 408 instances... identified head acceleration measuring 40g or higher, indicating a high-magnitude impact...Seventy percent (314) of these high-magnitude head impacts occurred during practice sessions ...only 22% of practice sessions were spent on tackling or blocking drills...these drills led to 86% of all high-magnitude head impacts sustained during practice. Based on their findings...a 10-minute reduction of time spent on tackling and blocking drills during each practice session could reduce the number of high-magnitude head impacts by 38%. Armed with the knowledge of which drills are more likely associated with severe head impacts as well as which drills produce greater numbers of head impacts per hour...organizers can develop a practice structure that will reduce exposure to high-magnitude head impacts.