Reports in recent years have demonstrated math teacher shortages in hard-to-staff school contexts due to high rates of teacher turnover. In this paper, I evaluate the impact of exposure to new, new-to-school, and emergency/unlicensed teachers on student math achievement on one recent cohort of Indiana students in 3rd through 8th grade. I find that students grow only 57% and 76% as much in their math scores in years they are exposed to new and new-to-school teachers, respectively, as compared to years they are assigned to returning math teachers. This negative impact is larger for both black students and students in poverty. Negative impacts on math achievement growth are also associated with higher proportions of new-to-school and emergency/unlicensed teachers in the school. I discuss the importance of these teachers in transition for understanding the disruptive effect of teacher turnover and its contribution to socioeconomic and racial achievement gaps. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]