Abstract: This thesis aims at investigating the beliefs of seven English high-school teachers about constructivist teaching and their classroom practices at a high school in a Northern area of Vietnam. Its purpose is to illuminate the conditions affecting their ability and willingness to reform teaching practices at their schools. Three distinct groups of participants are identified: Traditional Conservers, Neutral Pragmatists, and Adaptive Originators. For the Traditional Conservers, beliefs about teaching were strongly teacher-centered, supportive of traditional education methods, and shaped by beliefs that students should be obedient and passive learners.