School principals may be seen as mediating agents, standing at the school doorstep, between the extra-school and intra-school worlds. The principals' mediating role becomes more crucial during a time of education reform, which involves external demands on the one hand, and teachers' resistance to these demands on the other. This study explores how principals mediate between the demands of a national reform policy and teachers' attitudes and needs. In this qualitative study, 59 school principals were interviewed. Findings from the data analysis indicated that principals used two complementary mediation strategies: (1) mobilising the teachers towards the reform and (2) mobilising the reform towards the teachers. The mediating strategies used by principals are discussed, suggesting practical implications and further research avenues.