This case study investigates the development of the understanding of constructivist theory among students in a Masters level elementary teacher education program within a particular course. The focus of the study is a seminar entitled "Advanced Seminar in Child Development". The questions explored include: How do students' ideas of teaching, learning and knowledge develop within the context of their experience in this course? How do they come to understand constructivism? What are their definitions of constructivism? What is the course of the development of this understanding? The nature of the students' learning processes is examined through three sources of data: dialog journals, videotaped sessions and the instructor's reflective teaching journal. The study looks both at student development and instructional practice to further understanding of how student-teachers can learn to apply constructivist theory to their teaching and to understand the learning process, both within themselves and their students. Their development is placed in the context of Korthagen and Kessels's model of teacher understanding and practice, and within a broader context of principles of practice that emphasize a belief in equity and social justice. The case illustrates how the way student-teachers are taught theory can help them integrate their own ideas of learning and teaching with constructivist theory in order to think critically about their own practice in an ongoing developmental manner. (Contains 2 tables and 6 notes.)