de-Stalinization, political reform launched at the 20th Party Congress (February 1956) by Soviet Communist Party First Secretary Nikita Khrushchev that condemned the cult of personality and the crimes committed by his predecessor, Joseph Stalin, destroyed Stalin’s image as an infallible leader, and promised a return to so-called socialist legality and Leninist principles of party rule. This caused profound shock among communists throughout the world—who had been taught to admire Stalin—severely damaged the prestige of the Soviet Union, generated serious friction in the international communist movement, and contributed to uprisings in 1956 in Poland and Hungary. (See also Khrushchev’s secret speech.)