Frank was born into a Croatian-Jewish family, but converted to Catholicism at the age of 18 and attended the gymnasium in Osijek.

[4] Frank's initial political involvement included a critique of the People's Party (of Josip Juraj Strossmayer), joining the opinion of ban Levin Rauch.

In 1880, the Croatian poet August Šenoa characterised Frank in the following manner: The infamous Zagreb attorney […] degrades and befouls all that is Croatian, first to the benefit of the Magyars, now of the Austrians […] Frank is a political louse, who served Rauch, then the Swabian Generalkommando […] he offered himself to the Orthodox voter in Pakrac, bragging about […] protecting Serbian interests.

In 1895, after an incident in which students from Zagreb publicly burned the Hungarian flag in front of Emperor Franz Joseph, a rift formed in the party as Folnegović and others condemned that act.

By 1897, Frank had become the true leader of the Croatian states' rights movement, advancing to president of the party after Starčević's death.

[7] After Peter I Karađorđević came to power in Serbia in 1903, Frank's attention increasingly turned to opposing any rapprochement with the Serbs, unlike the majority opinion represented by the Croato-Serbian Coalition.

Unlike Ante Starčević, that was anticlerical, Frank considered to be useful collaboration with Catholic church in Croatia.

In the later stages of his career, he appeared as a man of confidence to the Viennese authorities, often acting secretly on their behalf.