UN field operations constitute a large and global network of technically sophisticated and complex organizations operating under very difficult circumstances. The number of operations and personnel deployed on these operations will vary over time with the opening and closing of missions, but since 2002, there have been between 50,000 and 120,000 civilian, police, and military personnel deployed at any one time across 16 to 32 operations. It is no small task to support this large multinational population in often hostile environments where host nation resources are either minimal or non-existent. The responsibility for this falls to the UN Department of Field Support (DFS). This chapter will explore the many roles and functions that DFS plays in support of the UN’s Peacekeeping and Political missions.