Purpose: This study tested a moderated mediation model of school leadership effects on teacher instructional practices. Specifically, the authors focused on the mediating effect of teacher professional communities and the moderating effect of instructional climate on the relationship between school leadership and teacher instructional practices. Design/methodology/approach: The authors collected data from 958 teachers working in 72 middle and high schools in Türkiye and employed multilevel structural equation modelling (MSEM) with Bayesian estimation to predict structural links between the study variables. Findings: Results affirmed a full mediation model where school leadership practices exerted indirect effects on teacher instructional practices through promoting teacher professional communities. The authors also found significant moderating role of instructional climate in the effect of school leadership on teacher professional communities and instructional practices. Originality/value: This study illuminates the contextualized nature of school leadership by concluding that the effect of school leadership on teacher professional communities and instructional practices is closely tied to the extent to which a high-quality instructional climate is established in schools.