Math anxiety has been studied since the 1950s. Researchers have examined the manifestations and effects of this condition in students, teachers, parents, and other populations. Elementary teachers with math anxiety have been the focus of researchers for several decades, and findings have revealed relationships between math anxiety and teacher beliefs, instructional strategies, student achievement, and other variables. However, very little attention has been given to math anxiety in secondary mathematics teachers (SMTs). Researchers who have investigated math anxiety in SMTs have found that there are similar relationships between math anxiety and instructional strategies and student achievement as there are in elementary teachers. This dissertation sought to continue the work done by researchers in the last decade by examining SMTs with math anxiety through new lenses. Specifically, the first study presented in this dissertation examined the characteristics common to and different from SMTs with math anxiety and those without math anxiety. This study further categorized the participants with math anxiety into relative levels of anxiety and examined similarities and differences among these levels. The second study in this dissertation explored the experiences of SMTs with math anxiety, both within and across the levels of math anxiety, to develop an understanding of the teaching practices of this population, as well as the contexts in which they feel most mathematically anxious. Findings from these studies indicate that SMTs with math anxiety share many of the attributes of elementary teachers with math anxiety. For example, SMTs who have taken more undergraduate mathematics coursework and have taught higher levels of mathematics tend to have less math anxiety than their counterparts who have taken fewer classes and taught lower levels of math, which is similar to findings about elementary teachers with math anxiety. However, there are distinctions to be made between mathematically anxious SMTs and elementary teachers. First, the participants in these studies stated that they found math beautiful and generally had positive things to say about math, even while recognizing the anxiety that math could cause them. Second, while elementary teachers with math anxiety have been shown to shy away from teaching higher levels of mathematics, several of the participants in these studies requested to teach courses they felt anxious about. Finally, SMTs with math anxiety often employ student-centric teaching practices, which is contradictory to findings on elementary teachers with math anxiety. The findings from these studies carry implications for many stakeholders, including researchers, teachers, and math teacher educators. Future research should investigate the following: math anxiety in diverse populations of SMTs; the effect mathematically anxious SMTs have on their students' math achievement and beliefs about math; and the effect of math anxiety on those who chose not to enter STEM fields. [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.]