The Four-Power Treaty (四ヵ国条約 Yonkakoku Jōyaku?) was a treaty signed by the United States, Great Britain, France and Japan at the Washington Naval Conference on 13 December 1921. It was partly a follow-on to the Lansing-Ishii Treaty, signed between the U.S. and Japan.
By the Four-Power Treaty, all parties agreed to maintain the status quo in the Pacific, by respecting the Pacific holdings of the other countries signing the agreement, not seeking further territorial expansion, and mutual consultation with each other in the event of a dispute over territorial possessions. However, the main result of the Four-Power Treaty was the termination of the Anglo-Japanese Alliance of 1902.
- Ian H. Nish, The Anglo-Japanese Alliance: The Diplomacy of Two Island Empires 1894-1907, The Athlone Press, London and Dover NH, first published 1966.
- J. Chal Vinson The Drafting of the Four-Power Treaty of the Washington Conference, Journal of Modern History, Vol. 25, No. 1 (Mar., 1953), pp. 40–47
-  – containing the full text of the Four-Power Treaty