Some youth leagues around the United States have made it illegal for players to head the ball in concerns that more head injuries are occurring. The leagues are responding by making it, in some cases, an indirect free kick offense for a player to intentionally head the ball. Referees should be aware of their league rules, knowing what to enforce. There is mixed reactions to these new rules from the officiating community, but it is in the interest of the health of the kids. Concussions have been a hot topic in all sports recently, and referees should know the protocol for what to do in case of a concussion or other head injury during a match. You can find this protocol for youth sports here. When in doubt, you should advise the coach to have their player sit out and get checked by a medical professional.