This paper concerns NATO's developing field of "Complex Operations", which includes developing institutional and operational capabilities in such areas as Counterinsurgency (COIN), Stability Operations, and Security Force Assistance (SFA). The paper explores the nature and pressing challenges presented by Complex Operations in an effort to begin a practical approach to them while theories and doctrines are worked out. Issues covered include the strategic context of anarchic environments, the nature of complexity and the "indirect" approach, and a review of COIN as a complex operation. Focusing on the human element, it introduces the concepts of a "New Heroic Age" and implications and roles for "functionaries and warriors." After reviewing the challenges and benefits of multinational operations, the author presents several conclusions and recommendations for NATO's doctrine, training, and educational development of personnel.