The article presents the development of the idea of a nation by comparing constitutional and social processes in Slovenia and Ukraine from the second half of the 19th century to the end of the 20th century. Upon examining the documentary and narrative sources on the formation of the Ukrainian and Slovenian nations, the authors point out that both Slovenians and Ukrainians co-existed within one country – the Austro-Hungarian Empire – as well as to the chronological and thematic similarity of historical independence movement processes in both countries, focusing on the period of Austria-Hungary, as well as on the time after World War I and World War II