Purpose: The purpose of this paper is to explore how Ontario principals make sense of difference within student populations and how this sensemaking influences how they do their work. Design/methodology/approach: The paper reports on a qualitative study in Ontario, Canada that included 59 semistructured interviews with school principals from English public, secular school districts in Southern Ontario. Findings: Four themes emerged in principals' descriptions of student populations: perceiving everyone as the same, or homogeneous; perceiving visible differences associated with particular religions, race and cultures; perceiving invisible or less visible differences, such as academic differences, socioeconomic status, mental health issues, gender identity and sexual orientation; and perceiving both visible and less visible differences through an inclusive lens. When asked about how their understanding of difference influenced how they did their work, principals' responses varied from not influencing their work at all to influencing practices and activities. Participants' context -- both personal and local -- influenced some of the work they did in their role as school principal. Lastly, multiple sources of disconnect emerged between how principals understood difference and the practices that they engage in at their school site; between their sensemaking about difference and diversity and preparing students for the twenty-first century competencies as global citizens; and between principals' understanding of difference and diversity and existing provincial policy. Research limitations/implications: Study insights not only contribute to an existing body of literature that examines principals' sensemaking around difference, but also extend this line of inquiry to consider how this sensemaking influences their professional practice. These findings pose additional research questions about how to approach principal professional learning for inclusive and equitable education. For example, even though principals are contractually responsible for students in their care, why is it that their efforts toward equitable and inclusive schooling appear to be limited to the school site and not the wider community? Practical implications: Study findings can be used to inform principal preparation programs and professional learning opportunities. Namely, these programs should provide the skill development required as well as the time needed for principals to reflect on their local context and beliefs, and to consider how their local context and beliefs are connected to larger societal efforts to create a more inclusive and equitable society. Social implications: School leadership is integral to creating and building more inclusive and equitable public education that improves all students' success at school. As Ontario's general population becomes increasingly diverse, it is imperative that principals support success for all students; this can only happen if they understand the complexity of difference within their student populations and beyond, how to address these complexities and how their own understandings and beliefs influence their leadership practices. Originality/value: Although other papers have examined how principals make sense of difference and diversity in student bodies, this paper also explores how this sensemaking influences how school leaders do their work.