The majority of research on second language (L2) classroom code-switching has aimed to identify the functions for which teachers choose to employ the first language (L1) and L2 in their classroom, with little research investigating the underlying factors regulating these language choices. This study employs classroom observations and semi-structured interviews to examine teachers’ use of their students’ L1 in five multileveled tertiary foreign language (FL) classrooms (Chinese, French, German, Japanese, and Spanish). It aims to determine the extent to which teachers employ the L1, the reasons underpinning this usage, and what implications, if any, this knowledge could have for L1 use in FL education in the future. The results suggest that the cultural and educational backgrounds in which FL teachers were themselves educated may have an influential effect on their teacher code-switching practices and pedagogical approach. The author suggests the need for FL teachers to also consider their students’ needs and adjust their practices accordingly as opposed to teaching based solely on their own L2 learning experiences.