This study explores whether the relationship between departmental leadership (i.e. group-oriented and development-oriented departmental leadership) and the interpersonal characteristics of professional learning communities (PLC) (i.e. collective responsibility and reflective dialogue) varies between departments, depending on whether teachers display traditional or constructivist beliefs. The data were collected from 197 teachers in 30 departments in 26 Flemish (Belgian) secondary schools via an online teacher survey and then analysed using multi-group path analyses. The results show no differences depending on teachers' educational beliefs. However, teachers with a group-oriented departmental leader experience more collective responsibility and report a higher frequency of reflective dialogue in their department.