This case study examines the effect of coteaching on the development of a student's professional knowledge. The study analyzes the student's perceptions of her experiences in a yearlong seminar course of math teaching in elementary school, conducted at a teachers college in Israel. The course was interdisciplinary and taught jointly by two lecturers--one from the discipline of mathematics and the other from the discipline of academic literacy. Analysis of observations, interviews, and documents illustrates the change in the student's perception of her professional knowledge--both academic and practical--regarding math teaching, as well as the contribution of caring coteaching to this change. The main conclusion of the study is that caring coteaching considerably enhanced the student's professional knowledge. This conclusion is in line with the rather limited literature dealing with this topic. (Contains 1 figure and 1 note.)