The study discussed in this paper focuses on the responses of mathematics teachers to the fundamental transformation of the Namibian educational system. As described in this qualitative study, changes to the educational system transformed the social context of mathematics teaching in fundamental ways. The findings of this study reveal that the mathematics teaching self-concepts and beliefs of the mathematics teachers were powerful determinants of the ways in which change was interpreted and implemented in the classroom. The themes of beliefs and self-concepts played crucial roles in the teachers' instructional practices and classroom discourse. Data analysis suggests that changes to the self-concepts and beliefs of the teachers affected instructional practices and classroom discourse. This study gives rise to important implications for mathematics teacher development in the context of educational change. [PUBLICATION ABSTRACT]