Leading educational change in university academic degree programs is complex and challenging. As academic middle leaders, program leaders play a crucial leadership role in enabling and sustaining quality learning and teaching practices in their degree programs and their middle leading practices have the potential to shape practices of student learning, teaching, professional learning, and researching associated with these programs. Previous educational research has explored individual program leader roles, behaviours, and motivations, as well as context-specific program leadership challenges and effectiveness. Despite the recognised importance of the role of program leaders in facilitating educational change, there is a dearth of research into the nuances of academic middle leading practices and practice conditions that shape transformations in academic degree program development within university sites. The purpose of this in-depth qualitative philosophical-empirical inquiry (Kemmis & Mutton, 2012; Kemmis, Wilkinson et al., 2014) was to critically examine academic middle leading practices and practice conditions associated with academic program development within one Australian university. Empirically, the study critically analysed and evaluated the middle leading practices and practice conditions in multiple program practice sites, and philosophically, the study employed contemporary practice theory to interpret empirical data and provide insights for practice theory development. The critical social practice theory framework underpinning the study was informed by the theory of practice architectures (Kemmis & Grootenboer, 2008), theory of ecologies of practices (Kemmis, Wilkinson et al., 2014), and site-ontological practice theory (Schatzki (2003, 2005). Through these theoretical lenses, academic middle leading practices were explored in multiple case study discipline-based schools (departments) across four groups (faculties) to elucidate the 'sayings', 'doings' and 'relatings' constituting these practices, and how these practices interact with other educational practices (student learning, teaching, professional learning and researching). Additionally, the cultural-discursive, material-economic and social-political practice architectures of these sites were scrutinised to illuminate the particular site-specific practice conditions that were enabling and constraining these practices. Participants encompassed former and current program leaders, teachers and students, who had engaged in program development initiatives. Utilisation of multiple qualitative data collection methods over time, comprising field observations, one-on-one narrative interviews, focus group discussions, document collation and digital photography, facilitated an in-depth study of practices from multiple perspectives. Data was analysed using inductive and deductive thematic analysis, content analysis, narrative analysis and image analysis methods. [...]