Purpose: The purpose of this study was to investigate how socio-religious dynamics influence (and are influenced by) principals in Islamic schools. Design/methodology/approach: This qualitative case study took place in Semarang, Indonesia. Data were collected via semi-structured interviews with school leaders along with school site observations. To frame the study, we drew from both Indonesian and international scholarship to understand extant perspectives on the context and on the ways that principals influence socio-religious thinking and practices in schools. Findings: Findings suggested that principals' personal experiences and beliefs are central to the ways that socio-religious thinking and practices are manifest in their school. Principals practice more progressive or conservative leadership by influencing the degree to which the school is (a) an open or closed system, (b) inclusive or exclusive in their practices and (c) plural or unitary in their teaching. In making decisions along each of these continua, principals in Islamic schools "curate" a socio-religious educational environment. Originality/value: This paper contributes to the literature on principals and socio-religious dynamics in schools by discovering specific continua of practice that collectively suggest a more conservative or progressive interpretation of Islam. As this area is understudied in educational leadership, the study makes a foundational empirical contribution, suggests theoretical constructs heretofore unexplored, and advances the notion of principal as curator of educational practice.