The monograph examines the parliamentary aspect of the activities of the constitutional democratic party of Russia at the beginning of the 20th century represented by its faction in the III State Duma of the Russian Empire (1907-1912). The first part of the study "On the Threshold of the III Duma" examines the organizational state of the constitutional democratic party on the eve and during the III State Duma of the Russian Empire (1907-1912). The electoral law of June 3, 1907 and the attitude of the cadets to it are analyzed. The election campaign for the election of deputies of the State Duma of the Russian Empire of the third convocation (1907-1912) is being considered in the light of the participation of the constitutional democratic party in it.