Graduate teaching assistants (GTAs) play a crucial role in North American colleges. At a mid-Atlantic, land grant institution, GTAs instruct 34,000 undergraduates per semester. Given this scope, GTAs exert a powerful influence on undergraduate learning, yet little is known about their teaching beliefs in relation to their classroom practices. This exploratory study aims to address this gap. Eleven GTAs were interviewed, and their teaching was videotaped to compare their teaching beliefs and classroom practices. The results revealed that GTAs hold teacher-centered beliefs about content but more student-centered beliefs about learning. The implications of these findings regarding GTA training are described.