Changes in instructional approaches play an increasingly significant role in teachers’ lives and student learning. Greater demand for providing students with active learning is, therefore, put upon teachers. However, within the context of tertiary education in ESP in Vietnam where traditional beliefs challenge teachers’ practice changes, such study has not been investigated so far. As teacher beliefs are intertwined with teacher change, this paper offers insights into how teacher beliefs about the nature of teacher change influence their change process in ESP classes. The data discussed in this paper include interviews, observations, and planning meetings with Science teachers at a Vietnamese university. The findings reveal how teachers had positive beliefs about the change process, understanding more about the roles they played as agents of change and implemented active learning activities relevant to their current practices. The findings also contribute to the knowledge of how lecturer beliefs in this context may be attributed to their change initiatives and potential future actions. Pedagogical implications for teachers to reflect on their own practices and enhance their beliefs about the capacity for change over time are also presented.