This study examined eleven K-8 interns’ perceptions of their mathematics mentoring support provided to first-year teacher interns and factors that influenced their ability to teach mathematics. Semi-structured interviews revealed that district and grade-level campus mentors provided the greatest amount of mathematics instruction and pedagogically based support to interns. Three factors most instrumental in developing the ability to teach mathematics were (a) manipulative use, (b) planning of classroom instruction and activities, and (c) execution of the lesson.