The current exploratory study used data on students in grades six through 12 in North Carolina to examine the effectiveness of their mathematics teachers. Its purpose was fourfold: (1) to identify teacher qualification indicators that are most important for predicting students' math scores; (2) to empirically identify teacher qualification profiles; (3) to examine relationships between typology membership and math scores; and (4) to investigate how the effect of typology membership differs across subgroups of low-performing students. Investigating how qualification typology affiliation influences students' mathematics gains can help school district administrators make informed decisions about the teachers they should recruit, hire, and place to work in mathematics classrooms to improve students' scores. Results of three separate Variable Importance Analyses (VIAs) including a systematic literature review and two random forest regression algorithms showed 10 of the 11 teacher qualifications indicators examined predicted students' math scores. Only special education certification was not predictive of students' scores. Of the 10 significant variables, experience and teachers' math and non-math test scores were the most predictive of math gains. Findings from a Latent Class Analysis (LCA) of the 10 most important teacher qualification predictors showed teachers were affiliated with one of eight mutually exclusive qualification typologies. Findings of VAM analyses showed, middle and high school students assigned to the most qualified teachers scored significantly higher than the overall mean. In contrast, students placed with the least qualified teachers had significantly lower gains. Pairwise comparisons showed there were significant differences in the effectiveness of teachers across some clusters. Results with low-performers in the middle grades demonstrated the most experienced and qualified teachers were the most effective overall while students placed with the least experienced and qualified teachers scored significantly lower overall. Results of pairwise comparisons showed mean differences in effect between the most experienced and qualified teachers and their less-credentialed counterparts were significant. Findings also demonstrated students with disabilities scored higher than the overall mean when placed with experienced teachers and English Language Learners scored higher when taught by content experts. Based on a discussion of the main findings, implications for policy and future research are discussed. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]