The Balfour Mission, also referred to as the Balfour Visit, was a formal diplomatic visit to the United States by the British Government during World War I, shortly after the United States declaration of war on Germany (1917).

The diplomatic history of World War I covers the non-military interactions among the major players during World War I. For the domestic histories of participants see home front during World War I. For a longer-term perspective see international relations (1814–1919) and causes of World War I. For the following (post-war) era see international relations (1919–1939). The major "Allies" grouping included Great Britain and its empire, France, Russia, Italy and the United States. Opposing the Allies, the major Central Powers included Germany, Austria-Hungary, the Ottoman Empire (Turkey) and Bulgaria. Other countries also joined the Allies. For a detailed chronology see timeline of World War I.