This study aimed to find out the sources of foreign language student teacher anxiety experienced by Turkish EFL student teachers throughout the teaching practicum using qualitative data collection tools. 150 student teachers completing their teaching practicum as part of their graduation requirement at Anadolu University Faculty of Education English Language Teaching Program participated in the study. The research tools were diaries kept by student teachers and semi-structured interviews conducted with 30 of the participant student teachers. Constant Comparison Method was used to analyze the qualitative data. The analysis of the data revealed six main categories as the sources of foreign language student teacher anxiety: students and class profiles, classroom management, teaching procedures, being observed, mentors, and miscellaneous. Each source of foreign language student teacher anxiety is described and exemplified with extracts from student teachers' diaries or interview records. The findings are discussed along the recent literature on foreign language student teacher anxiety. Suggestions for foreign language teacher education programs are also provided. (Contains 1 table.)