This survey-based study examined how the intensity of the beliefs of novice in-service teachers about reform-based mathematics instruction changed as they crossed the threshold into their first year of teaching. It also investigated the relationship between the influence of new mentors, or "transitional faculty," including mentor teachers, instructional coaches, and administrators, along with curriculum materials, and the changes belief intensity. Results obtained indicated belief changes were highly influenced by transitional faculty and curriculum materials. This study highlights the importance of creating systems to improve mentor selection and training so the work of university personnel is not undone during the novice's first year of teaching.