The First Austrian Republic (German: Republik Österreich) was created after the signing of the Treaty of Saint-Germain-en-Laye on September 10, 1919—the settlement after the end of World War I which ended the Habsburg rump state of Republic of German-Austria—and ended with the establishment of the Austrofascist Federal State of Austria based upon a dictatorship of Engelbert Dollfuss and the Fatherland's Front in 1934. The Republic's constitution was enacted in October 1, 1920 and amended on December 7, 1929. The republican period was increasingly marked by violent strife between those with left-wing and right-wing views, leading to the July Revolt of 1927 and the Austrian Civil War of 1934.

In September 1919, the Habsburg rump state of German-Austria was given reduced borders by the Treaty of Saint Germain, which ceded German-populated regions in Sudetenland to Czechoslovakia, German-populated South Tyrol to Italy and a portion of Alpine provinces to the Kingdom of Serbs, Croats and Slovenes (Kraljevina Srba, Hrvata i Slovenaca, or SHS). Despite Austrian protests this treaty also forbade Anschluss, or union of Austria with Germany, without League of Nations consent. The new Republic was created by the will of Allies who did not want the defeated Germany to expand its borders.