In this study, eleven K-8 mathematics urban interns' perceptions of their mentoring support systems and factors that influenced their ability to teach mathematics were examined. 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. Four factors hindering interns' abilities to teach mathematics included (a) mathematics-specific skills; (b) instructional-based strategies, but not necessarily math-specific; (c) mentoring-support assistance; and (d) general or non-content specific hindrances.