In recent years, a group of teacher educators has developed a method of teacher education that incorporates practices that provide guidance about how to teach along with a principled vision of teaching that supports teachers to use the practices with judgement. Sometimes termed "core practices-focused teacher education" (Forzani, 2014, p. 358), this approach seeks to support teachers in developing a repertoire of carefully selected instructional practices, and a principled personal vision which guides prospective teachers in their use. This vision centers students' ideas and views the job of the teacher as being responsive to their needs (Windschitl et al., 2012). In this study, I examined the learning of PTs in a core practices-focused math methods related to their developing understanding of core practices and personal vision. I investigated the learning opportunities related to personal vision in the methods course and explored how learning about core practices and personal vision took shape over time. I found that opportunities to experiment with core practice and analyze their enactment supported PTs to make connections between the core practices and their personal visions. Over time, the PTs developed an understanding of how the core practices could be used to achieve ambitious goals. They also increased the detail, and in many cases added new ambitious principles to their personal visions for mathematics teaching. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]