As the leader of the Sousa Band, Sousa was very busy. He chose the music for each concert. Because the band was made up of a unique combination of instruments, Sousa had to adapt the written music for each song to the musicians in his band. Sousa also helped make managerial decisions, including the design of the band's uniform and which towns they would visit on tour.

Most important, Sousa was the band's conductor. A band conductor, like a symphony conductor, is on stage with the musicians. The conductor interprets how the music will be played. During a performance, he tells the band how to play by moving his body and baton. Since it can be hard for the musicians to hear each other play, the conductor also sets the tempo (speed of playing)and makes sure all the musicians play together. Some conductors are very dramatic and emotional, but not Sousa. His movements were energetic, but controlled and efficient. When he moved, his band responded. With a small wave of his baton, Sousa could command a very loud roar or absolute silence.