The Constitutional Democratic Party was formed in Moscow on October 12-18, 1905 at the height of the Russian Revolution of 1905 when Tsar Nicholas II was forced to sign the October Manifesto granting basic civil liberties.
With some socialist and revolutionary parties boycotting the election to the First State Duma in February 1906, the Kadets received 37% of the urban vote and won over 30% of the seats in the Duma.