Mathematics is integral to today's world, but many students fear solving arithmetic problems. In the U.S., more than 82% of students in grades 7th through 10th fear math. In 2021, 80% of Florida high school students failed Algebra I end-of-course exam. Math anxiety has negatively impacted students' social cognitive, and academic skills. This basic qualitative study aimed to explore Florida high school math teachers' perceptions of math anxiety, understand, and learn their best practices for identifying math-anxious students and explore the instructional strategies they believe are effective in mitigating math anxiety for high school students. The theoretical framework was Albert Bandura's Social Cognitive Theory (SCT). The research questions which guided this study included: How do Florida high school mathematics teachers identify math-anxious students? What instructional strategies are used before, during, and after a math anxiety attack in a student? What instructional strategies do math teachers believe are successful in reducing math anxiety? Fourteen Florida high school mathematics instructors were recruited using purposeful and snowball sampling methods. During one-on-one Zoom interviews, /participants were asked 24 semi-structured open questions using the Teacher Instructional Strategies for Math Anxiety (TISMA) questionnaire. Data were then analyzed using thematic analysis. Fourteen themes emerged from the three research questions. Data revealed that students with math anxiety exhibited physical meltdowns, avoidance behaviors, and a lack of confidence. Further, the instructional strategies that teachers perceived most effective in alleviating high school students' math anxiety before, during, and after a math lesson were relationship building, positive communication, positive reinforcement, providing a safe environment, offering small groups, collaborating with parents and school officials, motivating students to have a positive mindset, providing extended time, playing music, and using reverse assessments. Ultimately, teachers believe that having positive communication, providing positive reinforcement, and ensuring a safe environment will reduce math anxiety. It is recommended that educators, school officials, and policymakers focus on developing professional development that identifies math-anxious students, differentiated instructional strategies for math-anxious students, designed classroom management strategies that foster positive relationships with students, parents, and the community, and provides support for collaboration and exchanging information about students' difficulties. [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.]