India in the last two decades has introduced several policy reforms to improve primary school mathematics teaching and learning, especially to make it more accessible for children. One such policy, National Curriculum Framework – 2005, outlines the need for making mathematics relevant to all children and connecting school mathematics to students’ lives. Based on these reforms, the National Council of Educational Research and Training (NCERT) developed new primary school mathematics textbooks. These books are a radical departure from traditional mathematics textbooks, as they explicitly restructure its form, pedagogy and mathematical content. The crucial enabling link in actualising transformational ideals in textbooks are, the teachers. Yet, both in India and globally, very little is understood on how teachers use textbooks in their teaching. To fill this gap, my study explores how teachers view and use textbooks in a reform context. The study adopts a participatory view of the relationship between the textbook and the teacher; which is both influenced by the textbook’s features as well teachers’ thinking. The study explores the cases of ten primary school teachers in Grades 4 and 5, in four government schools of Delhi. Data were collected from classroom observations, semi- structured teacher interviews, and textbooks. Thematic analysis was used to analyse the textbooks, classroom observations as well as interviews. The textbook analysis reveals that several pedagogical changes are introduced within the textbook. The reformed textbook challenges the authority relations between school mathematics and the learner. Additionally, social justice messaging is implicitly embedded within the textbook. Teachers in turn make textbook related choices at two levels: first, at the level of task selection; second at an interpretive level. Challenging the predominant understanding of textbooks-centric teaching, my findings show that teachers use a range of strategies to engage with the textbook. These include following the textbook as a script, customising it to fit their own notions of mathematics teaching and institutional realities, as well as avoidance of the textbooks and the subject all together. There are two important implications of the study. First, in relation to producing reform oriented textbooks, the thesis argues for a simultaneous focus on teachers must be maintained, so that textbooks become educative materials for professional development. Second, the study also highlights the significance of institutional and cultural opportunities and barriers in enabling teachers’ productive interpretations of textbooks.