The Jazz Lab Ensemble, under the direction of Larry N. McWilliams, is the flagship of the program, and enjoys the reputation of being one of the best collegiate bands in the country. The band rehearses five hours per week and tours throughout the United States and Europe. All students must audition for this ensemble. The band has performed at the Montreux Jazz Festival in the summer of 1985 and in the summer of 1997. In March, 1988, the ensemble won the Collegiate Division Outstanding Band Award at The University of Missouri-Kansas City Jazz Festival, performing on the evening Festival Concert. Since 1980, the band has received numerous honor band and individual outstanding musicianship awards at the Elmhurst College Collegiate Jazz Festival (Chicago), a feat repeated in 1993 and again in 1996, when the band was named overall award winner and performed on the evening concert, and seven members received outstanding musicianship awards; in 1994 they received the outstanding band and four outstanding musicianship awards. In the spring of 1999, the ensemble was one of eight bands selected to perform at the National Collegiate Jazz Festival in Mobile, Alabama, where they took more awards than any other ensemble, including the top overall performer, the top saxophonist, the top trombonist and the top vocalist.

In the summer of 1997 and 2001, the Jazz Lab Ensemble performed at the Montreux Jazz Festival in Montreaux, Switzerland, the Brienz Jazz Festival in Brienz, Switzerland, and The North Sea Jazz Festival in Den Haag, Holland.

The Related Links box includes two excerpts from an October 2006 concert.