This paper investigates the challenges experienced by some Australian school educators in implementing differentiated instruction (DI) at a large secondary school. A small-scale study was conducted using individual, semi-structured interviews with teachers and school leaders. Using thematic analysis, three major themes were identified, namely: teachers' barriers to implementing DI, school leaders' constraints to implementing DI, and pre-service to in-service exchanges and sharing about DI. Findings from teachers revealed limited school resources, student behaviour issues and inadequate time for planning and implementation. School leaders also identified time as an impeding factor but also reticence by experienced teachers to use DI. Teacher education courses are not clear about DI as a comprehensive teaching framework suitable for all students. Results highlight the need for further research at the teacher educator, teacher and school leader level to remove existing barriers, constraints, and misunderstandings about DI to ensure maximum learning opportunities for all students.