This paper explores how schoolteachers in Kazakhstan engaged with the Renewed Content of Education (RCE) that has been introduced by the Government, and how changes in their beliefs and understandings influenced classroom practice. The study draws on the ecological model of teacher agency and elaborates on factors that contribute to the formation of teacher agency. The study used a mixed methods research design and is based on data collected over two years in rural and urban schools across three regions of Kazakhstan. Altogether, 227 teachers having different levels of experience with the new curriculum were involved in focus group discussions. The findings demonstrate that the majority of teachers acknowledged the value of the RCE, its short- and long-term benefits for students, and the broader aim of boosting the economic competitiveness of the country. At the same time, the findings suggest that, while a surface change occurred in teachers' beliefs, their pedagogical practices, and the learning context, there is limited evidence that the teachers moved fully to new ways of teaching and embedded the principles of the RCE in practice. Through our findings, we verified the centrality of socially dynamic relationships in educational change. Teachers shared agency in developing their own rules and routines for collaboration. This paper adds to research on educational change in an international context by showing that the scope for teacher agency in reform implementation increases when teachers are able to develop deep reform-oriented beliefs, discourses, and pedagogical understanding.