Despite initiatives to increase and broaden participation in science, technology, engineering, and mathematics (STEM) fields, women remain underrepresented in STEM. While U.S. girls and women perform as well as, if not better, than boys and men in math, research results indicate that there are significant declines in girls' math self-efficacy, interest, and ambition as early as middle school. These decreases are associated with awareness of negative stereotypes viewing math as a predominately male domain. The classroom is one context for developing self-efficacy beliefs and gender-role stereotypes. The purpose of this quantitative study is to examine the role that students' perceptions of the academic and emotional support provided by their math teacher has on adolescents' math self-efficacy, math outcome expectations, and math interest. Social Cognitive Career Theory provides a theoretical framework for the study. Researchers collected data used for this study through a larger study (NSF grant #0624724). Data was collected from 230 students in sixth, eighth, and 10th grade to answer the research questions. Items from the Beliefs, Belong, and Behavior Survey provide measures for students' perceptions of Math Learning Environment, Math Self-Efficacy, Math Outcome Expectations, and Math Interest. The results of the study found that the relationships among math learning environment, specifically students' perceptions of the academic and emotional support provided by their math teacher, and the other SCCT variables were as predicted by the modified SCCT model. Students' perceptions of the academic and emotional support provided by their math teacher influences their math self-efficacy, math outcome expectations, and math interest. There were gender differences observed in the fit the modified SCCT model. Learning environment influenced the expected outcomes of taking advanced math courses differently for boys and girls. There were also gender differences in students' perceptions of teacher support, math self-efficacy, math outcome expectations, and math interest, with the greatest differences found between sixth grade girls and the other gender-grade groups. Finally, there was a relationship between girls' perceptions of the effect that taking math courses would have on relationships and their math interest, a relationship not observed in boys. Implications for researchers and practitioners are provided. [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.]