This book examines teacher agency in implementing English as a Foreign Language (EFL) curriculum reform in the Chinese university context. It theorizes the concept of teacher agency from a sociocultural theory perspective and draws on a study conducted in a conservative and less developed area in China. The book uses Engeström's activity theory and Vygotsky's concept of the Zone of Proximal Development (ZPD) to understand the nature and extent of teacher agency in adapting one’s teaching with respect to beliefs, knowledge, and instructional practices. The study concludes that curriculum reform in China needs to shift from reliance on 'top-down' policies to 'bottom-up' implementation that mobilizes local understandings and practices. One of the implications of this study is that transformative teacher education programs aimed at developing teacher pedagogical agency require that teachers have ongoing opportunities to design, develop, and evaluate curriculum-based mediational means.