The Conference of World Communist and Workers' Parties held in Moscow in November 1957 was the largest gathering of world Communists since the birth of Marxism. Scholars have long assumed that the Communist Party of the Soviet Union (CPSU) dominated the conference. Newly declassified archival records and memoirs indicate that the idea of convening a conference and issuing a joint declaration was proposed by both the Chinese Communist Party (CCP) and the CPSU. During the conference the CCP leader, Mao Zedong, played an important role. Mao's extemporaneous remarks at the conference shocked the leaders of the CPSU. His comments on the Soviet intraparty struggle, his blunt remarks about nuclear war, and his declaration that China would overtake Great Britain within fifteen years created doubts and dissatisfactions in the minds of the delegates and cast a cloud over the conference. The Moscow Declaration also revealed incipient Sino-Soviet disagreements, portending Beijing's challenge to Soviet leadership in the socialist bloc. Thus, the Moscow Conference was a turning point for Sino-Soviet relations.