The various beliefs about mathematics and its role in society led to differing beliefs about what it means to learn mathematics and how best to teach it. Mathematics education research and organizations such as the National Council of Teachers of Mathematics (NCTM) champion a combination of constructivist and sociocultural approaches to mathematics teaching and learning. Within this paradigm, mathematics teachers are cast as guides in their students' individual meaning-making experience. However, since mathematics is at the heart of science and technology, which are in turn the basis of the new global, knowledge-based economy, mathematics achievement scores on standardized tests are inexorably tied to national policy discourses of global competitiveness. Meeting the "global challenge" has resulted in government policies which reflect a view of effective mathematics teaching focused on accountability and measured outcomes. Underlying such policies is a positivist view of mathematics as a fixed body of facts and procedures which students need to internalize. Mathematics teachers function at the nexus of these differing beliefs about mathematics teaching and learning. This dissertation offers a case study analysis of three high school mathematics teachers as they navigate different belief systems while making professional decisions related to their work. This study examines the periods of tension, conflict, reflection, and resolution teachers experience while managing competing goals. The study concludes with implications for teacher education, as well as recommendations for future research.