The Rhythm Section Jazz Band (RSJB) is an American jazz band based in Grand Rapids, Michigan. The ensemble was formed in June 2002 for the purpose of advocating the performance of American music from the first half of the 20th century. The ensemble refers to itself as a "Little Big Band" and is made up of 10 musicians: 2 alto saxophonists, a tenor saxophonist, a trombonist, a trumpeter, a pianist, a guitarist, a bass guitarist, a drumer, and a singer. Since its inception, the band has toured throughout the United States and has held over 155 recording sessions.