Sociologists have too long neglected the massive socio-political experiments undertaken by Marxist elites in Europe, Asia, Latin America, and Africa. The successes and failures of these experiments have great relevance for both sociology and society. The study of these experiments cannot be left to area specialists, nor is this necessary in view of the growing flood of information now available in English translation. Successes discussed include the demonstration that a socialist economy is not incompatible with rapid economic growth and the reduction of inequalities in income and living standards. Failures include (1) the persistence of very high levels of political inequality, (2) the persistence of worker alienation, (3) the persistence of sex inequalities, (4) the persistence of rural-urban inequalities, and, perhaps most serious of all, (5) the failure of the new societies to give birth to the new socialist man. Second-generation Marxist regimes in China and Cuba seem not to have been significantly more successful in most of these respects than the Soviet Union and its satellites in Eastern Europe. Nevertheless, the institutional realities of Marxism are dynamic and the task of monitoring these societies and their experiments continues.