In spite of the massive body of work reconceptualizing school mathematics in keeping with progressive approaches, research has shown that many school mathematics teachers still opt for more traditional methods. The present study sheds light on the mechanisms that shape mathematics teachers' knowledge, beliefs, and instructional practices and thereby sheds light on those factors that support or impede the adoption of more reform-based teaching methods in mathematics. By adopting a sociological perspective, the study explores the school mathematics culture based on reflective blogs published by high-school mathematics interns during the year of their professional and cultural socialization. A qualitative analysis of the blogs yielded 10 cultural codes, suggesting that these could be hegemonically reproduced and preserved by the schools' more experienced mathematics teachers, who also emerged as primary socialization agents during the interns' induction into the teaching profession. The findings are salient for teacher educators and mentors who aim to promote changes in the pedagogical practices in teaching mathematics in school.