While understanding children's mathematical thinking is an important part of what teachers need to know in order to be effective in the classroom, preservice coursework often fails to provide learning opportunities focused on this aspect of teaching. Using a videocase curriculum focused on children's mathematical thinking, the authors examined changes in preservice elementary teachers' knowledge of, beliefs about, and ability to analyze children's thinking. Results from a quasi-experimental study indicate that the videocase curriculum had little effect on participants' knowledge and ability to analyze children's thinking, yet a moderate effect on participants' beliefs about mathematics teaching and learning. [For the complete proceedings, see ED585874.]