A drum major or field commander is the leader of a marching band, drum and bugle corps, or pipe band, usually positioned at the head of the band or corps. The drum major is often dressed in more ornate clothing than the rest of the band or corps and is responsible for providing commands to the ensemble, leading them while marching, and directing them what to play, when to play, the dynamic or volume of playing, and what time to keep. The commands may be given verbally, through hand gestures, using a whistle or a baton, or with a mace. Although the drum major is the one conducting for the entire band to see and watch to keep time, the drum major is actually looking at the center snare's feet to keep time. The center snare is the leader of the drumline, and is the one who keeps the band in time while marching. They usually play, tap and/or rolls to set the tempo of how fast the band marches.

In addition, the drum major serves as the liaison between the band director and the band. Essentially, a drum major is the leader who keeps the tempo with the use of a baton or other forms of time-keeping, such as conducting. The drum major often holds the responsibility to keep the band organized and structured.