In the rush to implement STEM programmes in economically disadvantaged school districts, there is a pressing need to develop a stronger sense of what might be considered effective and appropriate STEM practices for diverse students. The aim of this study was to characterise the experience of implementing an integrated STEM Project-Based Learning (PBL) programme in an Australian secondary school located within a diverse, socio-economically disadvantaged community. To identify enablers and constraints in delivering STEM PBL in this context, the study utilised qualitative data from interviews with school teachers and leaders, school planning documents and an extended series of classroom observations. Key findings point towards the importance of building a school culture that supports innovative pedagogy; the need to purposefully scaffold the capabilities of teachers and students to engage with active learning; and the potential value of multi-dimensional assessment allowing students to demonstrate STEM proficiency through novel forms of evidence.