The Math Teachers' Circle (MTC) model is a widely implemented form of professional development that invites teachers to become practitioners of mathematics, thereby developing their fluency with mathematical practices. This article presents comparative case studies investigating the self-reported experiences of several MTC-participating teachers representing a range of mathematical backgrounds. Teachers' reflections were examined through the lenses of three themes: views of mathematics, approaches to pedagogy, and professional engagement and leadership. Cross-case comparisons suggest several ways MTCs may be able to improve their support of teachers' professional growth, for example through discussing mathematical mindsets and incorporating additional leadership opportunities.