Are leaders born or made? In other words, are leadership skills innate or can they be taught? The consensus is that leaders are made-but that people start with different levels of innate ability. Using this assumption as a jumping-off point, the authors of this chapter argue that the development of leadership skills is directly linked to a person's self-concept or identity. In exploring this identity-based model of leadership development, they discuss the key transitions and experiences that shape leaders' careers, such as taking a significant (and role-changing) step up the organizational ladder. They suggest that helping people make "identity transitions"-allowing them to shed outdated identities that hinder change and creating opportunities for them to practice (and make mistakes with) new identities is a key component of leadership development-and one that invites further research. This chapter was originally published as Chapter 22 of "Handbook of Leadership Theory and Practice: A Harvard Business School Centennial Colloquium."