Within the educational system, the role of assistant principal is vital. Assistant principals are the face of administration in most school districts, they comprise the largest group of administrators and largely determine school effectiveness and success. Despite the critical nature of this position, this leadership and management role is not properly understood or respected. This is reflected in the lack of targeted research and effective preparation programs aimed at the assistant principalship.This book examines two areas which are core to educational leadership theory and practice: assistant principals and the passage from teaching to administration. It describes the cognitive, social, and emotional challenges that new assistant principals encounter as they cross this administrative threshold and it contextualizes their narratives within psychological and sociological theories of change, transition, and socialization. A visual metaphor of cycles within cycles describes the four critical phases of their administrative journey. Also included are recommendations for aspiring and new assistant principals, regulatory bodies, professional development providers, and school districts. As administrative pools diminish and school leaders face increasing demands, there is an urgent need to prepare new assistant principals for this complex leadership transition.