Research fairly consistently demonstrates that teachers are an important measurable factor in student learning, yet few teacher characteristics are shown to be consistently related to student achievement. Using a state administrative dataset that matches individual students to their teachers over time, I find that math teachers' undergraduate performance, as measured by GPA (overall, math, and math education) and course hours (math and math education), is predictive of 5th grade math achievement. The effects of the teacher characteristics are mediated by years of experience and vary according to student types. (Contains 7 tables.)