Leadership development is a multifaceted phenomenon with a multitude of definitions and meanings requiring closer exploration. The aim of this study was to identify and investigate qualitatively different ways of understanding leadership development and categorize them from a complexity perspective. We conducted 21 semi-structured interviews with professionals and managers. Analysis using a phenomenographic approach revealed six categories and different ways of understanding leadership development: (1) one's own development, (2) fulfilling a leadership role, (3) personal development, (4) leader and organizational development, (5) collective leadership development, and (6) human development. The categories were arranged hierarchically according to increasing complexity. Our contribution recognizes more nuanced interpretations than previously identified and highlights underlying structures of complexity. The results help to empirically ground and elaborate current theories and distinctions within the field of leadership development research where similar patterns can be observed. They may assist researchers in making both their own and other's assumptions on leadership development explicit, as well as informing the practice of tailoring leadership development activities to better match individuals and organizational contexts.