Leadership development has taken on far greater import in recent years (Day, 2000, McCauley and Van Velsor, 2004, Murphy and Riggio, 2003, Pearce et al., 2006).Alternatively, simply click on amazon.com and type in the term "leadership" in the book category. I did this on 7 July 2007. It returned 223,726 results. Clearly, there is an insatiable thirst for knowledge about leadership. In our normal, everyday lives we frequently hear arm-chair analyses of peoples' leadership styles--be they corporate leaders, religious leaders, political leaders or civic leaders--as being "blank" types of leaders, further evidencing our perennial preoccupation with leadership, and all that it entails.Interestingly, in juxtaposition to the deep grounding of the articles that comprise this special issue is the fresh tilling of new, rich and fertile soil for cultivating our next generations of leaders in multi and varied organizational contexts.In contrast, in this special issue, the authors argue that the focus of leadership development should be greatly expanded to include a much broader array of behaviors and competencies and should include followers in the process of leadership development (see Pearce, 2004, Pearce and Conger, 2003).Most current leadership development efforts focus on transactional and transformational leadership and focus quite narrowly on individuals who occupy formal leadership positions or are being groomed to occupy such positions eminently.Indeed, most professionals--be they in the for profit, governmental or social sector--would most likely concur that developing a keen sense of different types of leaders, how they behave, and what they expect, is essential for success, no matter what the organizational context.Knowledge work relies on the, necessarily, voluntary contributions of skilled professionals: After all, knowledge workers can withhold their intellectual capital and they can take it with them if and when they choose to leave.Forgetting our formal academic descriptions of leadership, lay descriptions of leadership, at least implicitly, refer to patterns of behavior that seem (perhaps intuitively) consistent or related.The authors of the seven articles that comprise this special issue tackle a wide breadth of topics that are critical to the future of leadership development.The scope of this popular interest in leadership--what it is, where it comes from, how we develop and implement it--is readily apparent when one walks into any bookstore.Some focus on capacities, capabilities and behaviors while others focus on physical and spiritual dimensions of leadership.What they all have in common, however, is a deep and profound grounding on the historical research foundations of leader and leadership development.Accordingly, we need to rethink the very concept of leadership, and by extension, leadership development, in the age of knowledge work--and that is the very purpose of this special issue on leadership development.Some focus on leaders occupying roles, while others focus on leadership as a process.Leadership has long captured the interest of practitioners and academics, as well as the more general public.Primarily, however, as Peter Drucker identified nearly half a Century ago (Drucker, 1968), we have entered the age of knowledge work.The reasons for this are manifold and multiplying.Some document current best practices, while others offer agendas for future research.Some focus on lower to mid-hierarchical levels, while others focus on executive levels and yet others identify cross-level issues.Some approaches are general and some are specific.