Summary/Abstract: The article is devoted to the problems of national, sociocultural and confessional identity forming of the Southern slaves and Belarus nation in the ideology of the liberal political parties and public organizations; the research of the Bulgarian, Serbian and Belarusian national idea genesis in the political movements of Russia at the beginning of the XX century. Attitude towards the history of the Southern slaves and Belarusian ethnic question by both the All-Russian liberal (the Constitutional-Democratic party) and regional parties and organizations (“Belarusian Society“) is examined. Evolution of the views on the Southern Slavonic and Belarusians self-determination problems is observed: from ethnos recognition, definition of its settling territory, necessity for studying its cultural features to raising a question of the nation-building by the end of Great War.
