The Continuation War (Jatkosota, Fortsättningskriget, Советско-финская война (1941—1944)) was the second of two wars fought between Finland and the Soviet Union during World War II. It lasted from 25 June 1941 until 19 September 1944.

At the time it started, it was named by the Finns to make clear its relationship to the preceding Winter War of 30 November 1939 to 13 March 1940. The Soviet Union, however, perceived the war merely as one of the fronts of the Great Patriotic War against Nazi Germany and its allies. Great Soviet Encyclopedia, Finland, Moscow, 1974, ISBN 0-02-880010-9 Similarly, Germany saw its own operations in the region as a part of its overall war efforts of World War II.

The United Kingdom declared war on Finland on 6 December 1941, followed by its Dominions shortly afterwards. The Continuation War is a rare case of democracies declaring war on other democracies but the British Empire forces were not major participants in the war. Nazi Germany took part by providing critical material support and military cooperation to Finland. The United States did not fight or declare war against either party, but sent substantial matériel to the Soviet Union for use in the war effort against Germany and its allies.

Hostilities ended in 1944, and the formal conclusion of the Continuation War was ratified by the Paris peace treaty of 1947.