Based on an experiment we conducted in a university course about instructional planning that was guided by a constructivist perspective, we show in this article how future teachers consolidate their own personal knowledge of teaching. Emphasis is put on the construction of knowledge about the discipline being studied, while getting a sense of the diverse processes of making meaning and of professional development in which future teachers are engaged. Results show that even in the isolated context of university education, the developmental pathway of future teachers can be seen as a complex process of participation, where students begin to engage in the practices of the community. Constructivism is the frame of reference from which effective learning about teaching is analyzed by future teachers during the course. The study was based on a cohort of education students at Laurentienne University during 2003-2004.