Purpose: We study the role of school climate, and teacher task, and citizenship performance in mediating the effects of principal instructional leadership behavior on student achievement. Design/methodology/approach: Structural equation modeling was applied to data obtained from 302 Indian secondary schools to test a mediated-effects model. Findings: School climate was examined under two broad dimensions, the social and affective and the physical environment. Results of mediation analysis showed that the benefits of principal instructional leadership for student achievement are operationalized as an indirect effect. This indirect effect is realized primarily through the physical environment, and the in-role task performance of teachers. No significant contribution to the indirect effect through the social and affective environment was found. The latter, nonetheless, fully mediated the relationship between the instructional leadership and extra-role or citizenship behavior of teachers. These findings underscore the different and distinct mediating roles played by the social and affective, and physical dimensions of the school climate in our model. Originality/value: To the best of our knowledge, the reported associations between principal instructional leadership, school climate and student achievement that take into account both the in-role and extra-role job performance of teachers within the purview of a single framework are new. Also, this is the first study exploring these relations in an Indian context. © 2021, Emerald Publishing Limited.