text: In HS, A linebacker often makes the defensive "play" calls for the team. He will call which back to key on (Fullback or halfback), what coverage the secondary will play (man to man or various types of zone.... and will make calls for the Defensive line to shift left or right or to change fronts. \n\nThe calls that he is responsible for become more sophisiticated as he progresses through a system, and College LBs often have more responsibility than HS, and a Varsity HS linebacker has more responsibility than JV.\n\nAs for responsibilities on the field, some of the other answerers have been spot on. A LB generally is responsible for making tackles, and possibly covering the TE or RB out of the backfield on passing plays. They are also occassionally called on to Blitz...