Purpose: There is an extensive body of contemporary educational literature concerning teachers' professional development (PD), but little attention has been paid to the PD of principals, despite their vital role in improving student learning outcomes. The available literature on principals' PD deals with content and quality while mostly ignoring whether and how PD activities have an impact on leadership practices. In our study, we wanted to examine the extent to which principals perform learning-centred leadership practices and whether and how their practices are influenced by the PD programmes they have engaged in during the past twelve months. Design/methodology/approach: A total of 130 Turkish principals participated in the study. Using the SEM model, we examined the direct and indirect links between principals' PD and their self-perceived learning-centred leadership practices, with self-efficacy as the mediating variable. Findings: We found a positive, statistically significant yet weak relationship between principals' PD and their leadership practices, with self-efficacy playing a considerable mediating role. Originality/value: We argue that traditional types of PD activities can contribute to the leadership practices of principals, at least in countries where school principals are not adequately prepared for principalship positions. We suggest that such activities can contribute by providing newly appointed school principals with certain basic knowledge regarding effective leadership that many principals in developing countries are missing due to the lack of pre-service training. These activities can also strengthen principals' belief in their ability to overcome school problems and improve student learning. This, in turn, could motivate them to focus more on learning-centred leadership practices.