This special issue is special for several reasons. The first concerns its content, the application of complexity sciences to the study of leadership. Although ideas and methods from the sciences of complex systems are increasingly being applied to organizational dynamics including leadership, nowhere until now has there been a forum completely dedicated to a rigorous treatment of complexity applied to leadership. Moreover, agreed upon definitions and concepts hav not yet emerged and too often it seems that the lessons of complexity don't manage to go beyond a well-trodden metaphorical value. In contrast, this Special Issue goes in search of the rigorous thinking, the science and the mathematics that are required in the application of complexity reseraach to organizations and leadership.

This issue is also special for the rigor and clarity of thought that have gone into the articles. Although E:CO does not primarily focus on empirically-based research, we made an exception for this Special Issue because of the need for this kind research at this juncture of the field, and also because of the exacting mathematical and computational methods of many of the submissions we were happy to receive. This is an important development, and therefore we selected four of the six articles because they involve a high level of mathematical and computational modeling which are of such vital currency within complexity theory. Also encouraging is that these efforts are interdisciplinary. Contributions to this Special Issue come from a diverse set of researchers whose primary fields of study include: physics, mathematics, computer science, law and education as well as the more traditional areas of psychology, sociology and management.