In Scotland since August 2021, there has been a statutory requirement for aspiring headteachers (school principals) to gain the Standard for Headship (General Teaching Council for Scotland, Standard for headship. General Teaching Council for Scotland. http://www.gtcs.org.uk/web/FILES/Professional-Standards-2021/2021-Standard-for-Headship.pdf , 2021), primarily through a masters-level programme called Into Headship. This chapter presents the findings of a research project which explored the experiences of a cohort of aspirant school leaders undertaking Into Headship. The aim of the research was to gain a deeper understanding of how engaging in this process of professional learning impacted and influenced the leadership development of participants, their practices and preparedness for the headteacher role. An ecological model of agency (Priestley et al., Teacher agency: An ecological approach. Bloomsbury Academic, 2015) was used to shape the research design and to analyse the data. The chapter examines how the underpinning values, concepts, design processes and practices of Into Headship impacted the agency and sense of empowerment that participants had in terms of equipping them with strategies to navigate their way through political tensions, competing demands and expectations in leading school improvement. Taking a future-oriented stance, the chapter concludes by considering what lessons can be drawn from this study to enhance the development of future principal preparation programmes and create system-level sustainable pathways in for the preparation, recruitment and retention of high quality headteachers.