It has been widely acknowledged that teacher agency is significant in curriculum reform. Previous studies have shown that even in the contexts of policy-constraining where curriculum is pre-described and mandated, there is still scope for teachers to exercise agency. In the context of Vietnam where education system is highly centralised, few studies have explored the complexity of teacher agency in school context. This study investigates how EFL teachers in Vietnamese primary schools make sense of the current state-mandated English language curriculum, and how they translate the curriculum into practice. Data were collected from in-depth interviews and classroom observations. The views of social theory on agency were used as framework to analyse the data. Findings indicate that teachers appropriate the curriculum to fit their school contexts. Among the multifarious factors that affect teacher agency, the ways in which teachers position themselves in relation to the curriculum change, to colleagues and students is the strongest one. Teachers’ personal views, and institutional constraints affect how the curriculum is enacted.