One of the great challenges ensemble directors face is selecting high-quality repertoire that matches the musical and technical levels of their ensembles. Thoughtful repertoire selection can lead to increased student motivation as well as greater enthusiasm for the music program from parents, administrators, teachers, and community members. Common problems that can lead to overprogramming are presented, along with a discussion of Vygotsky's zone of proximal development and Csikszentmihalyi's flow theory as frameworks for considering how directors' repertoire choices can affect students' motivation and continued participation. (Contains 1 figure and 19 notes.)