Institutions of higher education have experienced a rapid increase in international student enrollment within a short period of time, especially in mathematics classrooms. It is therefore important for instructors to have the knowledge and skills to support international students in the learning of mathematics. There are few research studies of the experiences of faculty teaching mathematics courses to international students, a gap that serves as a motivation for this study. The purpose of this study is to explore the experiences of mathematics instructors when assigned to teach courses for international students. In particular, this study explores how instructors perceive and work with language barriers that international students encounter in the classroom as they learn mathematics while they are in the process of also learning English. Interviews with instructors teaching mathematics for international students were analyzed. The themes identified in this study highlight the challenges encountered by instructors, the teaching adjustments made by instructors, and instructors’ perceptions about the differences in classroom culture.