This chapter begins with a brief review of Forde (Issues of social justice and fairness in the development of aspiring head teachers. In: Bogotch I, Shields CM (eds) International handbook of educational leadership and social (in)justice (pp 1125–1143). Springer, 2014) which traces the evolution of values in education policy in Scotland and then proposes a model of headship as social activism to underpin development programs to support social justice leadership. We then present some of the key findings of our first project exploring headship (principalship) and social justice leadership, building on this model of headship in Scotland as social activism. We discuss the ways in which our initial construction of headship as social activism has been developed, by examining the relationship between values, political insight, criticality, and leadership, encapsulated in the idea of “critical leadership” praxis. Following this, we outline a professional learning program, Enhanced Political Awareness, designed to augment the mandatory headship preparation program by building critical leadership praxis with aspirant and serving headteachers. From the research study of this program, three key issues are identified, related to the practice of critical social justice leadership in school: authenticity, capacity, and safety. These issues are explored further through a second research project, a new case study of the social justice leadership of a Scottish headteacher. We conclude the chapter by arguing that authenticity, capacity-building, and safety/risk-taking are facets of critical social justice leadership.