Research in mathematics education shows that new mathematics teachers struggle to implement reform teaching practices that they learned in their teacher preparation programs. In this study, the researcher observed and interviewed three new mathematics teachers (within five years of graduation) to further explore the question of why new teachers use or do not use what they learned in their teacher preparation program. The study uses an expanded version of Schoenfeld's decision-making theory of Orientations, Goals, and Resources. This theory proved useful in the analysis of the research data, providing a framework to incorporate and organize the numerous reasons suggested by the literature for why new teachers struggle to use what they learned in their teacher preparation programs. Results show that an orientation that reform teaching is the most effective way to teach mathematics, along with the resources of a reform curriculum, a team of teachers with similar reform orientations, and district support are all important factors in helping new teachers use what they learned in their teacher preparation program.