CPSU By PolitikalMatters Period: Jun 14, 1917 to Jun 14, 1922 Formative Period Period: Jun 14, 1923 to Jun 14, 1928 Moderate Rule Period: Jun 14, 1928 to Jun 14, 1953 Radical Rule Period: Jun 14, 1954 to Jun 14, 1964 Periof of Re;lative Openess Period: Jun 14, 1965 to Jun 14, 1986 Period of Political Stagnation Period: Jun 14, 1986 to Jun 14, 1991 Political Reform and Decline