After February 1917 the political system of Russian society (there were over 50 parties) moved from the right-wing and centrist organizations to the left. Black-Hundred unions, which stopped their activity after demise of Nikolai II, never revived. The Union of October 17 practically disappeared from the political arena too, despite the fact that a number of its members (M.V.Rodzyanko, A.I.Guchkov, I.V.Godnev) once were members of the Provisional Government.
In contrast to monarchists and Octoberists, the Party of National Freedom (Constitutional Democrats) increased its membership after February 1917 approximately 5 times, reached 70 thousand members, and occupied a strong positions in the first staff of the Provisional Government (Minister of Foreign Affairs P.N.Milyukov, minister of agriculture A.I.Shingarev, Minister of Railway N.V.Nekrasov etc.). The VIIth congress of the party, which took place in March, made a decision to define more exactly the program, in which it was written that Russia should be democratic and parliamentary republic. However no changes were made in the agrarian part of the program.
Decision on governmental cooperation with socialists was made at the VIIIth congress. A.A.Manuilov, D.I.Shakhovskoy and A.I.Shingarev were the members of the first coalition government.
After the February revolution of 1917 socialists-revolutionaries became extremely popular. The number of socialist-revolutionary party grew up to 400-600 thousand people (by different estimations). Left-wing socialist-revolutionary P.A.Aleksandrovich, the former Party of Labour member and later socialist-revolutionary A.F.Kerensky were among the first staff of Petrograd Soviet of workers' and soldiers' deputies. Socialist-revolutionaries occupied important posts in new governing bodies in Moscow, Novonikolaayevsk, Ufa and other cities. Organizational legal structures of this party were simultaneously being quickly restored, and by the end of May 1917 the socialist-revolutionary party had up to 800 thousand members.
At the III congress of the party, held on May 25 - June 4, 1917, the Central Committee was elected, the decision on formation of coalition Provisional Government and preparation of elections to the Constituent Assembly was adopted. The final state system of Russia was to be determined by the Constituent Assembly, which, in opinion social-revolutionaries would establish democratic republic. At the local level the authority should be handed over to bodies of local government (dumas and zemstvoes), which were elected in the democratic way. At elections to city dumas, held in August 1917, socialist-revolutionaries in most cases formed alliance with Mensheviks and won the majority of places.
The socialist-revolutionaries supported the cessation of war, struggle against imperialism of the warring countries, restoration of internationalism, protection and all possible strengthening of gains of the revolution. At the same time the left wing of the party was against defensive position, demanded to expand revolutionary movement to other countries to light the fire of global revolution. The right wing declared their support of war, loyalty to allies and necessity to break off with Bolshevism. They too, counter to the policy of the Provisional Government, spoke in favour of state regulation of production, control over foreign commerce and domestic trade. The socialist-revolutionary party was against authority usurpation and thought, that bourgeois parties must be deposed from the power in a gradual and democratic way.
Anarchists made an attempt to unite their isolated groups after the February revolution. In Moscow members of seven organizations on March 13, 1917 formed the Federation of anarchical groups. Anarcho-syndicalists managed to take control over unions of metal-workers, port workers, bakers, separate factory committees. In their beliefs anarcho-syndicalists gradually got rid of aspiration of immediate transformation of society into an anarchical one, while anarcho-communists were loyal to the idea of ungoverned, communistic society. Anarchists, except for anarchists-individualist, recognized the idea of joining the structure of Soviets, but only with the informational purpose. Dissociation of anarchical organizations did not allow them to make any serious influence on the political life of the country.
Mensheviks, who had not played any special roles in revolutionary events in February - March of 1917, managed to take a leading place in Petrograd Soviet, and also in a number of other Soviets. Originally they did not pretend to authority, but then under pressure of democratic public opinion and socialist-revolutionary party made the decision on joining the coalition government. However, Mensheviks could not render much influence on its policy.
The final delimitation with Bolsheviks took place at the unifying congress of Mensheviks, held on August 19-25, 1917 in Petrograd. At the same time struggle at the congress between different wings of Mensheviks led by A.A.Potresov, I.G.Tsereteli, F.I.Dan, Y.О.Martov, supporters of the Petrograd newspaper "Novaya zhizn (New life)" (N.N.Sukhanov etc.) brought to nothing all efforts to unite Menshevist forces. Group of Y.Larin and some other Mensheviks defected to the camp of Bolsheviks, Mensheviks-internationalists started publishing their own newspaper "Iskra (Spark)", and right-wing Mensheviks - magazine "Rabochaya mysl (Concept of workmen)".
Group of G.V.Plekhanov from May changed its name for All-Russia social democratic organization "Edinstvo (Unity)". Mensheviks, led by Tsereteli and Dan, continued their participation in the coalition government, protection of the country and struggle for global democratic peace. As a result, by the time of opening of the IInd congress of Soviets on October 25, 1917, Mensheviks were splintered and failed to resist Bolsheviks and their supporters.
The leadership of Bolsheviks's party after the February revolution could not right away develop a new strategy and tactics. At the beginning of March the Russian bureau of the Central Committee declared about counter-revolutionary character of the Provisional Government and necessity of formation of revolutionary-democratic government, but these ideas found no support in the majority of political organizations. Under influence of the moderate position of Petrograd committee and especially L.B. Kamenev, who returned from exile on March, 12, and also I.V. Stalin and M.K.Muranov Russian Bolsheviks actually supported Mensheviks and socialist-revolutionary party on many questions: relative support of the Provisional Government, pressure on it with the purpose of conclusion of the peace treaty and advancing of revolution. The tendency to organizational merge with Mensheviks found its expression in mass creation of united (Bolshevistic -Menshevist) party organizations and negotiations about integration.
However after the VII April All-Russian conference of Russian Social-Democratic Party of Workers (Bolsheviks) the order of things radically changed. V.I.Lenin supported an establishment in Russia of dictatorship of proletariat and poor peasantry as a prologue of the future global revolution, peaceful transition to the second stage of revolution and a handover of authority to Soviets, and also for the resolute breakup with the international and Russian Social Democracy. All this was not at first supported by Bolsheviks party leadership (V.P.Nogin, L.B.Kamenev etc.), but delegates of the April conference, after long discussions, basically approved the majority of items of Lenin's program. In July 1917 Lenin and his supporters, taking into account current conditions, skilfully corrected their policy.
In September Lenin demanded that the preparation for armed revolt be started, he considered, that Europe was "on the threshold of global proletarian revolution", and correlation of forces in the country is extremely favourable for armed seizure of authority by Bolsheviks. Lenin rejected all accusations of incitement of civil war, proving, that any "streams of blood" during it could not be compared to "seas of blood", shed by Russian army during the June offensive, which was led by Russian imperialists.