Various empirical studies have established the positive relationship between teacher professional community (PC) and participative decision-making (PDM) within schools. Considering that these relationships proved relevant to school improvement in different countries, a comparative approach will allow us to establish whether this positive relationship holds true for a wider range of European countries. This study presents results of this relationship using data from 35,000 secondary teachers in 22 European countries. Taking an exploratory approach, the study investigates the relationship between the presence of PC and the school actors involved in PDM. We are particularly interested in the level of active participation in decision-making by teachers, the school governor or counsellor, and by students, and the relative presence of PC. We find this relationship to be significant and positive, but varying in strength according to the actors involved in decision-making. Furthermore, the relationship is stronger across all countries studied when teachers are significantly involved in decision-making as opposed to when school counsellors or governors are more involved. Regarding student involvement in decision-making, its relationship with PC proved stronger when students could influence school rules or help choose teaching and learning materials. The relationships measured and compared across countries were tested for robustness by applying a test for measurement invariance of the PC latent concept and discussing its implications for the relationships of interest. After other relevant robustness checks, we conclude that, across all European countries studied, there is a positive relationship between PC and PDM in schools, with the involvement of some actors in PDM being more indicative of the presence of PC than the involvement of others.