This paper develops an understanding of underlying influences shaping leadership learning within a single organization. It is not an exploration of leadership but rather an explanation of how individuals learn how to lead. Through in-depth interviews with six directors of a UK multinational public limited company and, using critical realist grounded-theory, underlying causes have been identified that build upon existing research but then goes further to provide a systemic and integrated explanation of leadership learning. A model is suggested to illustrate how causal influences, operating in a particular context, influence how people develop their ability to lead. I argue that the metaphor of apprenticeship captures the essence of how underlying influences shape the long-term process of leadership learning: an apprenticeship perspective has significant implications to the efficacy and effectiveness of leadership development interventions.