The effort to create a Common Foreign and Security Policy is a manifestation of the broader movement for European integration. The CFSP aims to coordinate foreign and security policy among all of the member states of the European Union (EU). Pro-Europeanist states, led by France, consistently sought to increase coordination and cooperation among the continental states. On one level, CFSP and the concurrent push for a European Security and Defense Identity (ESDI) are designed to increase the potential military power of the EU. On another level, this drive for a foreign and security policy was originally a manifestation of autonomy and independence from the United States during the Cold War; however, since the end of the superpower struggle, the CFSP has emerged as a means to assert Europe's interests and influence in the global arena.

From the first steps of defense cooperation in Western Europe at the end of World War II, there have been various proposals and initiatives to coordinate foreign and security policies among the states of the region. Nonetheless, the most significant concrete steps toward integration occurred in the economic sphere. It was not until 1970 that the countries of the European Community began to officially consult on matters of foreign policy through the wider mechanism of European Political Cooperation (EPC), whose core purpose was to promote cooperation on foreign policy. The 1986 Single European Act increased the level of interaction and consultation among the members through the EPC.

In 1991, France and Germany proposed the establishment of a CFSP for the EU within the Maastricht Treaty. The ratification of the treaty in 1993 created the CFSP as the second of the three main "pillars," or areas, of the EU (the first was economic cooperation and integration, and the third was police and general law enforcement cooperation). Maastricht contained 11 provisions on CFSP and called for the EU member states to cooperate in international affairs and to adopt common positions on related matters, all the while pursuing multilateral action. The provisions also called for the EU to develop a "common defense" and for the Western European Union (WEU) to become the military arm of the EU. The WEU participated in operations including the Iran-Iraq War, the Persian Gulf War, and the Balkan Wars.

Concurrently, the WEU increased its operational capabilities and was tasked to develop ESDI. One technique to achieve this goal without dramatic increases in defense expenditures was the "double-hatting" concept, in which forces were assigned multiple roles. Under this concept, units could be assigned to both the North Atlantic Treaty Organization (NATO) (wearing one "hat") and the WEU (putting on a different "hat"). NATO retained its role as the main guarantor of peace and stability in Europe, but its focus was mainly on hard security threats to the national sovereignty or national interests. Meanwhile, the WEU became increasingly focused on soft security, including humanitarian operations, crisis management, and peace enforcement missions. The WEU's focus on these areas reflected the 1992 Petersburg Declaration, which designated the WEU as the body for these types of operations (the "Petersburg Tasks"). Hence the concentration of ESDI was on soft security missions and not a challenge to NATO. The WEU also oversaw the Western European Armaments Group (WEAG). By coordinating defense industries, WEAG could reduce redundancy and encourage efficiency among Europe's arms firms and thereby reduce procurement costs and increase resources for ESDI. Nevertheless, the WEU never fully reached its potential, as EU states remained constrained by budgetary and resource pressures. Instead, NATO remained the default security mechanism for the EU.

The role of a CFSP of the EU was further expanded in the Amsterdam Treaty, which came into force in 1999. It gives the EU the right to establish common strategies and provides the European Council the ability, under certain conditions, to impose decisions upon the member states through a system of qualified voting. The treaty also provided for the creation of the position of high representative for CFSP, a post to be held concurrently by the secretary-general of the EU's Council of Ministers. The EU's first high representative was former NATO secretary-general Javier Solana, who was appointed in October 1999. Finally, the Amsterdam accord provided for funding CFSP through the common EU budget.

The Treaty of Nice, which came into force in 2003, added additional measures for the CFSP, including an expansion of the areas under which qualified voting may enforce decisions. In addition, new powers were given to the structures of the CFSP. The treaty also accelerated the absorption of the WEU into the EU. By 2005, the main functions of the WEU, with the exception of WEAG, had been transferred to the EU.

In order to conduct the CFSP, the EU created several agencies and committees to support the high representative. Among these groups are the European Union Institute for Security Studies and the European Union Satellite Center. While these groups are primarily advisory bodies, the Political and Security Committee (PSC) is tasked with monitoring events within the transatlantic region or areas in which the EU has significant interests. In addition, the PSC provides opinions to, and monitors the enforcement of decisions of, the EU Council of Ministers. The PSC is directly responsible to the General Affairs and External Relations Council, which is composed of the foreign ministers of the EU member states.

The development of a CFSP by the EU is seen by many as a means to lessen the role of NATO and, by extension, the United States in European security. This perception is reinforced because of the ongoing fiscal constraints on defense expenditures that force states to fund their preferences in the security realm. The funding problem has also limited the ability of the EU to develop more significant security structures. In addition, many within the smaller European states perceive a CFSP as a means for more powerful states such as France and Germany to dominate the external and defense policies of Europe. Momentum for a stronger CFSP accelerated in the aftermath of the 2003 Iraq War, during which there were deep disagreements among the NATO allies over the propriety of the military action.

The main component of the CFSP became the implementation of ESDI through a European Security and Defense Policy (ESDP). The EU has declared that an ESDP is critical to the development of the second pillar, or CFSP, but also compatible with NATO. Steps toward an ESDP include the aforementioned transition of Petersburg Tasks and capabilities from the WEU to the EU. In addition, the European Council has created a range of bodies as a means to activate the ESDP. There is now an EU Military Staff and EU Military Committee. In order to give the EU significant operational capability, in 2004 the Council authorized the creation of a 60,000-member rapid deployment corps, the European Rapid Reaction Force (ERRF). In order to staff the ERRF, the EU relies on the earlier double-hatting arrangement so that member states can assign troops to both NATO and the ERRF.

ESDP has manifested itself in missions that either complimented ongoing NATO operations or were operations that the alliance chose not to undertake. These include EU Force (EUFOR), in which the EU has taken over the NATO-led mission in the Bosnian Conflict, and Operation Artemis, in which the EU deployed forces to the Democratic Republic of the Congo at the request of the United Nations Security Council.

Nevertheless, CFSP has been supported by the United States as a means of lessening America's share of the burden of European defense and promoting burden sharing. CFSP would also provide a means to allow the EU to undertake missions and operations that the United States chose not to undertake. It can be viewed as the continuation of the failed European Defense Community of the 1950s and a maturation, not diminution, of the transatlantic security relationship. Nonetheless, as with earlier efforts to develop ESDI, fiscal and political constraints continue to limit the development of the EU's CFSP.