Professional development of school leaders requires quality long-term professional development programs (Jensen, 2016; Sahlin, 2023). In addition to the choice of an appropriate program (Wright & da Costa, 2016), the organization and didactic approach of professional development trajectories (PDT) determine the perceived effectiveness by school leaders (Mdhlalose, 2022). The concrete transfer and sustainable implementation of the content of a PDT in the work context also poses a challenge (Mdhlalose, 2022). Insight into the effectiveness of PDT focusing on transfer to the individual’s context has improved over the past decades (Baldwin et al., 2017). However, little empirical transfer research is available on the effects of PDTs for school leaders (Daniëls et al., 2021). Even less research exists on the key factors that sustain the effectiveness of PDTs for school leaders after completion (Daniëls et al., 2021). One sub-question of a larger PhD project in the Flemish context (Belgium) was: which specific approach as part of the PLC participation during the 2-year PDT do school leaders perceive as effective for sustained action- and goal-oriented transfer of professional development and implementation of school development after completing the program? The research questions were answered using mixed methods research. An online survey (N=132) was completed at the end of the PDT with a specific organizational and didactic approach. Further, 24 of these school leaders completed a survey one year after completion, and participated in an in-depth interview. The data revealed that school leaders were above-average positive about the concrete perceived impact of their participation both immediately after the end of the program and one year after completion. After one year, the perceived impact of the PDT on their approach and capacity to reflect on school policy was rated positively by almost all the school leaders. Their participation mainly affected vision development and goal-oriented elaboration and implementation of a policy-based action plan. The results showed a strong appreciation of the PLC approach in function of goal- and action-orientation. Clear planning and organization of the sessions provided an enabling framework to work on content. When substantive, broad and concretely applicable content linked to questions/goals were central to PLC meetings, school leaders found this positive. When absent, school leaders experienced this as inhibiting motivation and transfer. Despite the intention of all PLCs to sustain collaboration at the end of the PDT, this was not achieved by all groups due to personal, school-related reasons as well as structural reasons.

Baldwin, T. T., Ford, J. K., & Blume, B. D. (2017). The state of transfer of training research: Moving toward more consumer‐centric inquiry. Human Resource Development Quarterly, 28(1), 17-28. Daniëls, E., Muyters, G., & Hondeghem, A. (2021). Leadership training and organizational learning climate: Measuring influences based on a field experiment in education. International Journal of Training and Development, 25(1), 43-59. https://doi.org/10.1111/ijtd.12206 Jensen, R. (2016). School leadership development: What we know and how we know it. Acta Didactica Norge, 10(4), 48-68. Mdhlalose, D. (2022). An analysis of the impact of the environment on the transfer of training in the workplace: A systematic review. International Journal of Research in Business and Social Science (2147- 4478), 11(10), 55-62. https://doi.org/10.20525/ijrbs.v11i10.2168 Sahlin, S. (2023). Professional development of school principals – how do experienced school leaders make sense of their professional learning? Educational management administration & leadership, 0(0), 17411432231168235. https://doi.org/10.1177/17411432231168235 Wright, L., & da Costa, J. (2016). Rethinking Professional Development for School Leaders: Possibilities and Tensions. EAF Journal, 25(1).