Only twice in its 93-year history did the RSDRP-CPSU fail to call a party congress more or less within the prescribed time-span – the ten-year lapse that followed the Fifth (London) Congress in 1907 and the 13-year gap after the Eighteenth Congress in 1939. In each instance the absence of a congress was a result in part of the current leader's disinclination to hold one, in part of the party's own atrophy, and in part of more pressing concerns of a military nature. While the congresses that did meet in the 1930s were dismal, predictable and perhaps avoidable affairs, the same cannot be said of those of the pre-revolutionary period.

The Russian Social Democratic Labour Party (RSDRP) accorded its congresses the position of being ‘the highest organ of the party’. Only such gatherings had the power to pass binding resolutions, to alter the party's programme, to amend its statutes, or to elect its central bodies. It is not surprising, therefore, that much of the early history of the party has been written around the struggles and the changes that occurred at its congresses, particularly the Second (1903), Fourth (1906) and Fifth. These three gatherings – all of which took place in the relative safety of western Europe – were large, long and expensive.2 Nevertheless, they were seen as essential in the building of the party and in the defining of its role. The Fifth Congress declared that henceforth congresses should be called every year by the Central Committee.