This study investigated the engagement in an inquiry process of six EFL (English as a foreign language) teachers from two Vietnamese universities, and how the inquiry process shaped the teachers’ professional learning, paying attention to cycles of reflection and co-construction of knowledge. Student-centred approaches relevant to English language learners were used as a content focus of teacher learning, and teacher inquiry was used as a tool to drive reflection and co-construction of new learning. In particular, the study investigated the process of enactment and reflection as the teachers applied student-centred approaches (SCA) while working to develop their pedagogical knowledge, improve their teaching practices, and engage in professional learning practice. The study lay within an interpretive paradigm and was predominantly qualitative, using a small amount of quantitative data from the questionnaire administered at the beginning of the study. Data were collected via a four-phase process comprising five data collection instruments. In Phase 1, an online questionnaire was sent out to a wider group of teachers from the two universities and was analysed descriptively to gather initial information about the teachers’ reported beliefs and practices to inform me as a researcher how to proceed the next stage of the study. Qualitative data were collected in Phases 2, 3 and 4 of the study. After the six teachers engaged in the inquiries, their classroom practices were observed to explore how they interpreted and enacted SCA. Most observed teaching sessions were followed by a debrief in which the teachers were asked questions to reflect on certain moments of their practice and to elicit the elaborative reasoning underpinning their classroom practices. The teachers then took part in group discussions, which gave them opportunities to present individual reflections on their practice and knowledge and at the same time established an understanding of how the teachers learned, developed their professional knowledge, and improved their professional practice. Finally, semi-structured interviews were carried out individually with the six teachers to gain insights into their learning experience after engaging in the inquiry process and interactive professional discussions with other teachers. The interviews also explored the teachers’ reported changes in cognition and practice, along with their concerns. The qualitative data were then analysed via an inductive thematic coding process and the use of vignettes. It was not my intention to triangulate data from these sources. Rather, the use of multiple data collection instruments added to the comprehensiveness, rigour, and saturation of the study and the teachers’ learning process. In this learning process, I sought to capture what the teachers communicated across the data collection instruments, each of which was designed to serve a particular purpose, rather than comparing them or integrating them. In brief, this study suggested that an inquiry-driven, practice-based, and interactive approach facilitated teacher learning both individually and collectively, and stimulated professional growth. Engaging in the process of inquiry fostered the teachers’ reflection on and self-evaluation of their practice and developed self-awareness of their classroom decisions. Interactive opportunities and collegial dialogues in the group (a learning community) helped the teachers to learn from each other, problem solve together, recognise different ways of doing things, negotiate different views, reconsider their beliefs and practices, shift perspectives and recognise the value of multiple positions. In both individual and collective learning endeavours, the process of learning placed an emphasis on the active and agentic engagement of the teachers and their reflective practice, embedding cognition, enactment and other aspects such as personal, contextual and socio-cultural factors. All of these were in line with constructivist and situative perspectives of learning.