This chapter explores the generic command problems for a military component within peace-support operations (PSOs), as well as the recent institutional evolution of the United Nations (UN) Department of Peacekeeping Operations (DPKO). In recent years UN military forces have found themselves involved in complex and volatile environments, both in terms of the nature of the conflict into which they have been deployed and the institutional arrangements that have prevailed. The effectiveness of new multinational structures and ad hoc coalitions is undermined by the inability of commanders to rely upon the certainties that underpin the cohesion of national command and control structures. The UN remains institutionally ill-equipped to deal with the wider problems of policy and operational coordination, as well as the specifically military concepts of command and control. Its fortunes in terms of institutional capacity to coordinate activities like Icarus, have risen and fallen, it still retains enormous value.