The First Austrian Republic, officially the Republic of Austria, was created after the signing of the Treaty of Saint-Germain-en-Laye on 10 September 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 on 1 October 1920 and amended on 7 December 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.

The Treaty of Saint-Germain-en-Laye was signed on 10 September 1919 by the victorious Allies of World War I on the one hand and by the Republic of German-Austria on the other. Like the Treaty of Trianon with Hungary and the Treaty of Versailles with the Weimar Republic, it contained the Covenant of the League of Nations and as a result was not ratified by the United States but was followed by the US–Austrian Peace Treaty of 1921.