Mathematics achievement is important for students' future career, pay, and opportunities. Understanding how students best achieve in mathematics has been a focus of many studies. The purpose of this study was to describe the relationship between the psychological state of mathematics teachers and student achievement in mathematics. Current literature on the topic of teacher effects and student achievement in mathematics focuses on fixed teacher characteristics, like degree earned and years of experience. This study focused on malleable characteristics of teachers. Specifically, efficacy, a teacher self-belief, and implicit theories of intelligence, a belief about others were studied in relation to student scores on a standardized test of mathematics. The dataset used was from the Educational Longitudinal Study of 2002 (ELS:2002) provided by the National Center for Education Statistics and consisted of 6,800 students. I performed multiple regression analysis in order to create best-fit models for the variables in question. As expected it was found that students of teachers who ascribe to an incremental view of intelligence tend to have higher mathematics achievement, when controlling for all other variables. An unexpected finding was that students of teachers with low self-efficacy tend to have higher achievement results than students of teachers with high self-efficacy, when controlling for other variables. Based on an unexpected interaction, the highest student achievement results in mathematics were students of female teachers with low efficacy and an incremental theory of intelligence. Also surprising is that the lowest student achievement results in mathematics were students of male teachers with high self-efficacy and an incremental theory of intelligence. [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/en-US/products/dissertations/individuals.shtml.]