This paper problematises "confidence" as a frequently used explanation for performance in the mathematics classroom. I report on an interview-based study of how some English "Advanced" level (16+) students who have chosen to study mathematics, and their teachers, speak about confidence with respect to the learning of mathematics. I outline what constitutes confident learners for these teachers and, differently, for their students and what the students feel teachers could do to improve the students' confident state. I discuss the implications of this for the education of prospective teachers of mathematics.