The ruling class is the social class of a given society that decides upon and sets that society's political agenda.
The sociologist C. Wright Mills (1916-1962), argued that the ruling class differs from the power elite. The latter simply refers to the small group of people with the most political power. Many of them are politicians, hired political managers, and military leaders. The ruling class are people who directly influence politics, education, and government with the use of wealth or power.
Analogous to the class of the major capitalists, other modes of production give rise to different ruling classes: under feudalism, it was the feudal lords, while under slavery, it was the slave-owners. Under the feudal society, feudal lords had power over the vassals because of their control of the fiefs. This gave them political and military power over the people. In slavery, because complete rights of the person's life belonged to the slave owner, they could and did every implementation that would help the production in the farm.
Mattei Dogan, in his recent studies on elites in contemporary societies, has argued that because of their complexity and their heterogeneity and particularly because of the social division of work and the multiple levels of stratification, there is not, or can not be, a coherent ruling class, even if in the past there were solid examples of ruling classes, as in the Russian and Ottoman Empires, and the more recent totalitarian regimes of the 20th century (communist and fascist).
Milovan Djilas said that in a Communist regime, the Nomenklatura form a ruling class, which "benefited from the use, enjoyment, and disposition of material goods," thus controls all of the property, and thus all of the wealth of the nation. Furthermore, he argued, the Communist bureaucracy was not an accidental mistake, but the central inherent aspect of the Communist system, since a Communist regime would not be possible without the system of bureaucrats.