Peace of Riga of 18 March 1921

 The Peace of Riga, also known as the Treaty of Riga (Polish: Traktat Ryski), was signed in Riga on 18 March 1921, between Poland, Soviet Russia (acting also on behalf of Soviet Belarus) and Soviet Ukraine. The treaty ended the Polish–Soviet War.

The Soviet-Polish borders established by the treaty remained in force until the Second World War. They were later redrawn during the Yalta Conference and Potsdam Conference.

World War I removed former imperial borders across Europe. In 1918, after the Russian Revolution had renounced Tsarist claims to Poland in the Treaty of Brest-Litovsk and the war had ended with Germany's surrender, Poland was able to re-establish its independence after a century of foreign rule.

The Russian Civil War presented an opportunity for Poland under the leadership of Józef Piłsudski to regain parts of the tsarist territories of the former Polish-Lithuanian Commonwealth which had been incorporated into the Russian Empire during the Partitions of Poland.