This study investigates whether the Student Mediation Model is useful for understanding how undergraduates learn from international teaching assistants (ITAs) teachers who are not from the United States and are not native English-speakers. The study examines a sample of over 8,300 students enrolled in beginning and more advanced calculus and computer science courses. Student grades and instructor evaluations were quantitatively analyzed to compare student achievement and satisfaction with instruction in courses taught by native English-speaking teaching assistants (NTAs) in comparison to courses taught by ITAs. Results suggest that students taught by ITAs in more advanced classes adapt to the quality of instruction. Students' grades and evaluations of the teaching assistants are not significantly different across NTA and ITA sections. Conversely, students in beginning courses appear to lack sufficient readiness to negotiate meaning with ITAs, resulting in lower communication and overall ratings of ITAs compared to NTA ratings. Despite this, the beginning students are able to marshall their efforts in order to achieve on a par with students in NTA sections. It is asserted that university administrators should try to avoid assigning ITAs to beginning courses, assigning them to more advanced classes instead. It is concluded that a Student Mediation Model may be better than an Information Transmission Model to explore how undergraduates learn from ITAs. (Contains 35 references.) (Author/NAV)