In this article we consider the importance of reflective practice and research attitude for the professional development of in-service teachers. Nine teachers engaged in an international master's course (in a Belgium and French university) were interviewed to obtain self-narratives. The two year full-time master's course aims to develop skills in educational science research. The interview was conducted at the end of the master's course to explore students' reflective practices and to evaluate the impact of the research attitude developed during the course on their reflective practices. From the results we can see that reflective practice differs among the teachers interviewed, especially between those of varying seniority. The research activities learned in the master's course enabled the teachers to develop and expand their reflective practice through analysis of their experience. The study highlights the need for regular and more guided support in improving reflective practice, especially for junior teachers.