The Concert of Europe was a general agreement between the great powers of 19th-century Europe to maintain the European balance of power, political boundaries, and spheres of influence. Never a perfect unity and subject to disputes and jockeying for position and influence, the Concert was an extended period of relative peace and stability in Europe following the Wars of the French Revolution and the Napoleonic Wars which had consumed the continent since the 1790s. There is considerable scholarly dispute over the exact nature and duration of the Concert. Some scholars argue that it fell apart nearly as soon as it began in the 1820s when the great powers disagreed over the handling of liberal revolts in Italy, while others argue that it lasted until the outbreak of World War I and others for points in between. For those arguing for a longer duration, there is generally agreement that the period after the Revolutions of 1848 and the Crimean War (1853–1856) represented a different phase with different dynamics than the earlier period.

The beginnings of the Concert of Europe, known as the Congress System or the Vienna System after the Congress of Vienna (1814–1815), was dominated by the five great powers of Europe: Austria, France, Prussia, Russia, and the United Kingdom. Initially envisioning regular Congresses among the great powers to resolve potential disputes, in practice, Congresses were held on an ad hoc basis and were generally successful in preventing or localizing conflicts. The more conservative members of the Concert of Europe, members of the Holy Alliance (Russia, Austria, and Prussia), used the system to oppose revolutionary and liberal movements and weaken the forces of nationalism. The formal Congress System fell apart in the 1820s but peace between the Great Powers continued and occasional meetings reminiscent of the Congresses continued to be held at times of crisis.

The Concert faced a major challenge in the Revolutions of 1848 which sought national independence, national unity, and liberal and democratic reforms. The 1848 Revolutions were ultimately checked without major territorial changes. However, the age of nationalism ultimately brought the first phase of the Concert to an end, as it was unable to prevent the wars leading to the Italian unification (by the Kingdom of Sardinia) in 1861 and German unification (by Prussia) in 1871 which remade the maps of Europe. Following German unification, German chancellor Otto von Bismarck sought to revive the Concert of Europe to protect Germany's gains and secure its leading role in European affairs. The revitalized Concert included Austria-Hungary, France, Italy, Russia, and Britain, with Germany as the driving continental power. The second phase oversaw a further period of relative peace and stability from the 1870s to 1914, and facilitated the growth of European colonial and imperial control in Africa and Asia without wars between the great powers.

The Concert of Europe certainly ended with the outbreak of World War I in 1914, when the Concert proved ultimately unable to handle the collapse of Ottoman power in the Balkans, hardening of the alliance system into two firm camps (the Triple Alliance and Triple Entente), and the feeling among many civilian and military leaders on both sides that a war was inevitable or even desirable.

The Concert of Europe describes the geopolitical order in Europe from 1814 to 1914, during which the great powers tended to act in concert to avoid wars and revolutions and generally maintain the territorial and political status quo. Particularly in the early years of the Concert, the Concert was maintained through the Congress System – sometimes called the Vienna System – which was a series of Congresses among the great powers to resolve disputes or respond to new issues.

The Concert of Europe is typically viewed in two distinct phases: the first from 1814 to through the early 1860s, and the second from the 1880s to 1914. The first phase, particularly before the Revolutions of 1848, is sometimes known as the Age of Metternich, due to the influence of the Austrian chancellor's conservatism and the dominance of Austria within the German Confederation, or as the European Restoration, because of the reactionary efforts of the Congress of Vienna to restore Europe to its state before the French Revolution. The ultimate failure of the Concert of Europe, culminating in the First World War, was driven by various factors including rival alliances and the rise of nationalism. The Congress-focused approach to international affairs continued to be influential in the later League of Nations, the United Nations, the Group of Seven and other multi-lateral summits and organizations.

The Concert of Europe arose from the coalitions which fought against revolutionary and Napoleonic France. The great powers of Austria, Prussia, Russia and the United Kingdom, had combined with a number of minor powers to defeat Napoleon for the final time in the Hundred Days. In the wake of this victory, these four great powers formalized their partnership in the Quadruple Alliance. In time, France under the Bourbon Restoration was established as a fifth member of the Concert, after the Congress of Aix-la-Chapelle ended the occupation of France and established the Quintuple Alliance. The Ottoman Empire was later admitted to the Concert of Europe in 1856 with the Treaty of Paris following the Crimean War recognized and guaranteed Ottoman territory.

The idea of a European federation had been already raised by figures such as Immanuel Kant, Gottfried Leibniz, and Lord Grenville. The Concert of Europe drew upon their ideas and the notion of a balance of power in international relations, so that the ambitions of each great power would be restrained by the others: