After a brief survey of certain achievements the author examines the process of difficulties built-up and subsequent crisis which hit the Communist movement in the 2nd half of the 20th century. As the author demonstrates, the crisis wad caused by the external, objective factors that bore on the movement (abrupt change of the situation in the world and within countries, the diverse anti-Communism (as well as subjective reasons related to the major errors in the parties' activities and activities of the Communist movement as a whole. Among causes of the crisis one has to mention inadequate attention of the parties to changes of the situation, wavering between dogmatism and denial of principles, inability or unwillingness to overcome theoretical and political disagreements that arose among parties etc. The author offers a concise characterization of the Communist movement at the beginning of the 21st century and possible perspectives of the Left movements' development are outlined.