This paper discusses the effects of large-scale studies, including international comparative studies and national studies using nationally representative samples, on policy making and practices pertinent to mathematics education in Taiwan, through the lens of Taiwanese societal and cultural characteristics. Taiwan has been through several successful and unsuccessful initiatives to apply the findings of large-scale studies to change or formulate policies with regard to mathematics curricula, assessment reform, approaches to teaching and learning mathematics for specific groups of students, and criteria for primary school teacher certification. Examination of these policy initiatives may reveal the mechanisms of success and failure when applying large-scale study results to education reform. These education reform insights may provide valuable information to other countries.