<p>This study explored how teacher-tailored student evaluation of teaching (TT-SET) augmented with peer observation of teaching (POT) impacted on academics’ pedagogical reasoning in a Vietnamese university. The qualitative case study within the constructivist paradigm used multiple data collection methods. Detailed analysis developed findings through descriptions of individual academics’ experience of the intervention and analysis across participants (using thematic analysis). The intervention encouraged academics to reflect on their practice. This reflection promoted changes in their understandings of practice, actions to refine practice, future plans, and other outcomes (e.g., enhanced confidence, self-efficacy, sense of autonomy, and collegiality). However, there were several challenges which varied among the participants, including perceiving TT-SET as lacking reliability and validity, limited learning from junior peers, disagreement with feedback and lack of sensitivity, and limited time for POT and changes. The findings also suggested that among other factors, the nature of the peer relationship, which is under the impact of the Vietnamese Confucian collectivist culture, was important to successful implementation of the intervention. The theoretical framework developed for this study helps explain the changes in academics’ pedagogical reasoning, particularly reflection. The study contributes to the area of tertiary teacher development, both theoretically and practically. It offers insights into how such an approach may be effective, particularly in the context of Vietnamese higher education, and provides guidance for both practice and policies. It identifies what needs to be done to improve the implementation of the intervention. It also offers ideas for leaders to make institutional policies to support academics’ professional learning and development. Its findings contribute to understanding how the intervention works, and why it works in the Vietnamese context and also of academics’ reflection and reflective practice. The study includes recommendations for the use of TT-SET augmented with POT for promoting teacher reflection that may lead to changes in practice by addressing necessary conditions for the intervention to be effective. Further research is recommended into the nature of the peer relationship and the characteristics of the peer for POT (e.g., in terms of age, experience, gender, and discipline), the impact of contextual factors, the role of leaders in creating the culture of the learning community, the timing of the intervention, and the use of students’ learning outcomes to evaluate the effectiveness of changes.</p>