The third official meeting of the Communist International included delegations from more than 50 different national structures and took place in the back-drop of two major events; the failure of the German revolution and the introduction of New Economic Policy in Soviet Russia.

[7] The Communist Party of Azerbaijan delegation included Gazanfar Musabekov, Ibrahim Abilov [az] and Mikheil Kakhiani.

[8][9][10] The Communist Party of Austria delegation included Franz Koritschoner,[11] Joseph Frey,[11][12] Jacob Riehs[13] and Karl Steinhardt.

[15] The CPA leader William Earsman travelled together with Jack Howie (Australian delegate to the RILU congress), reaching Great Britain and from there went to Moscow where they arrived on 13 June 1921.

[16][18] Freeman died in the Aerowagon experimental monorail crash on 24 July 1921, along with his close friend Commissar Artem.

[22] Mikhail Yaroshevsky arrived in Moscow on 1 June 1921, as a correspondent of Argentinian trade union and Communist Party newspapers, and assisted the congress.

[29] Other CPGB delegates included Norah Smyth,[30] Tom Mann,[13] F. L. Kerran,[6] Thomas Quelch,[31] Joseph J. Vaughan,[32] J. T. Murphy,[33] Harry Pollitt,[34] Ellen Wilkinson[33] and William J. Hewlett [ru].

[36] Rose Witcop of the Anti-Parliamentary Communist Federation travelled Moscow to (unsuccessfully) negotiate for 'associate membership' in Comintern for her faction at the congress.

[41] Another four Communist Party of Czechoslovakia cadres had been named as delegates to the congress, but they had been denied passports and were thus unable to travel.

Per Trason (1955) this positioning could be explained as linked to the adoption of the NEP which included ideas of emphasizing closer connections to broader popular masses akin to those of Šmeral.

[51] The Bukharan delegation protested against the measure to only allowing consultative status, arguing that Bukhara was a 'prominent, significant stronghold of the proletarian revolution in the East'.

[56] At the time of the 2nd World Congress of the Comintern in 1920 one of two boats used by the Bulgarian Communist Party to cross the Black Sea was captured by Romanian forces and Vasil Kolarov, Georgi Dimitrov and Kosta Yankov [bg] had been jailed.

[56] In the lead-up to first congress of RILU, the U.S. communist organizer Ella Reeve Bloor travelled to Winnipeg where she sought to convince the One Big Union leader Robert B. Russell to attend the event.

[61] His participation was effectively managed by the Far Eastern Secretariat of the Comintern in Irkutsk, a process that the Communist Party organization in China was unaware of.

[61] M. Díaz Ramírez had received a credential from José Rubio to represent the Communist Section of Cuba in the Mexican Region at the Third Congress.

Two Japanese delegates were present, Taguchi Unzo and Yoshiwara Gentaro, participating in individual capacity with consultative vote.

It was to display the history of mankind, from the Stone Age, to antiquity (ancient Egypt), feudalism, capitalism, the victory of the Communist International and building the future.

It was conceptualized as a mass worker peasant opera with orchestra, chorus, dancers performed in large amphitheater.