The DPKO traces its roots to 1948 with the creation of the UNMOGIP and UNTSO. Up to the late 1980s, peacekeeping missions were operated by six officials in the United Nations Office of Special Political Affairs, which was headed first by Under-Secretary-General Ralph Bunche, and subsequently Brian Urquhart and Marrack Goulding. From the beginning, peacekeeping operations operated with a clear doctrine that applied to its traditional or classical peacekeeping operations for inter-state ceasefires: peacekeepers did not take sides or discharge firearms, save in self-defense, or meddle in politics.
The official DPKO was created in 1992 when Boutros Boutros-Ghali took office as Secretary-General of the United Nations; its creation was one of his first decisions. Goulding became under-secretary-general (or USG) for peacekeeping with Kofi Annan appointed as his deputy. The role of the DPKO, however, wasn't clarified until June 1992, when Boutrous-Ghali issued a plan to strengthen the UN's capacity for preventative diplomacy and peacekeeping, entitled An Agenda for Peace.
DPKO is split into two main offices: the Office of Operations and the Office of Mission Support.
Included within the Office of Mission Support (or OMS) are the logistics and administrative divisions, which provide logistics, personnel, and financial support services to DPKO missions. OMS is responsible for determining financial reimbursement to UN member states for their contribution of Contingent owned equipment, troops, and services to peacekeeping missions. Letters of Assist are an important part of this. Also part of DPKO are Mine Action, Training, Best Practices, and Military and Police Divisions.
A March 2007 United Nations General Assembly Resolution titled “Strengthening the capacity of the Organization in Peacekeeping Operations” has called for the re-structuring of the department and the establishment of a separate Department of Field Support. Whereas the new entity serves as a key enabler by co-ordinating the administration and logistics in UN peacekeeping operations, DPKO concentrates on policy planning and providing strategic directions.
This re-organisation was paralleled by a DPKO reform effort launched in 2005 entitled 'Peace Operations 2010', which further pursues reforms initiated by the 'Brahimi Report' Report of the Panel on United Nations Peacekeeping Operations. This included an increase in personnel, the harmonization of the conditions of service of field and headquarters staff, the development of guidelines and standard operating procedures, and improving the partnership arrangement between the Department of Peacekeeping Operations (DPKO) and the United Nations Development Programme (UNDP), African Union and European Union. One area of this reform effort has been the development of clearer internal doctrine or guidance for UN peacekeeping. The highest level DPKO doctrine document was issued in 2008, known as the 'capstone' doctrine.
The bulk of peacekeeping operations funding is appropriated much like the general budget, but permanent members of the Security Council are required to pay a larger share, and all states are free to contribute additional funding, equipment, or other services to missions of their respective choices.
As of 2010, DPKO leads 16 different missions in Africa, the Caribbean, the Middle East, Americas, Europe and Asia. Serving in these missions are over 100,000 uniformed and civilian personnel. Total approved annual expenses are over US$5 billion for the period July 2006 to June 2007.
At an October 2006 press conference, the then USG Jean-Marie Guéhenno announced that peacekeeping operations had reached an all-time high, and will continue to expand as UNIFIL and UNMIT reach full strength, and if a UN mission enters Darfur.