The Progressist Party (Russian: Прогрессивная партия, прогрессисты) was a group of moderate Russian liberals organized in 1908; it had 28 deputies in the Third Duma and 48 in the Fourth. Its most prominent members were Ivan Nikolaevich Efremov, Alexander Konovalov, and Pavel Ryabushinsky. In the last two Dumas the Progressists entered into a coalition with the Constitutional Democrats, and in the Fourth Duma they were part of the Progressive Bloc. After the February Revolution Efremov and Konovalov became part of the Provisional Government.
Michael T. Florinsky (ed.), McGraw-Hill Encyclopedia of Russia and the Soviet Union (1961), pp. 455-6