The Croatian Peasant Party is an agrarian political party in Croatia founded on 22 December 1904 by Antun and Stjepan Radić as Croatian Peoples' Peasant Party (HPSS). The Brothers Radić believed that the realization of Croatian statehood was possible within Austria-Hungary, but that it had to be reformed as a Monarchy divided into three equal parts – Austria, Hungary, Croatia. After the creation of Kingdom of Yugoslavia in 1918, Party requested for the Croatian part of the Kingdom to be based on self-determination. This brought them great public support which culminated in 1920 parliamentary election when HPSS won all 58 seats assigned to Croatia.

Svetozar Pribićević was a Croatian Serb politician in Austria-Hungary and later Kingdom of Yugoslavia. He was one of the main proponents of Yugoslavism and a federalized South Slavic state which would later turn out to be Yugoslavia. However, he later became a bitter opponent of the same policy that was promoted by King Alexander I.