At the top of the social pyramid is the small ruling elite composed of the top leadership of the party, government, security forces, mass organizations, and the various branches of the economy. The ruling elite also includes members of the cultural and intellectual elite who, by virtue of their political loyalty and willingness to serve the regime, share in the privileges usually reserved to the top leadership. By lending their talents to the party cause, however, these individuals often lose some of the prestige and deference traditionally enjoyed by the intellectual elite. The main criterion for membership in the ruling elite is power derived from approved ideological orientation and political manipulation. Most members come from peasant or worker families and are veterans of the communist movement of the interwar period. Membership in the ruling elite is accompanied by considerable insecurity because it is highly dependent on political loyalty and correct interpretation of ideology. A change in official policy can deprive a member of his status and of all his privileges. Since the end of World War II, Bulgarian society has been extremely mobile. Industrialization and socialization of the economy have created thousands of new blue- and white-collar jobs. The attendant increase in educational opportunities has made it possible for individuals to gain the skill and background required to fill these jobs and, thereby, move up the social ladder. This mobility has been aided by the government's determined effort to reshuffle society by improving the social status and opportunities of the formerly underprivileged groups and by denying them to the formerly privileged ones. Because education has traditionally been the main determinant of status, social mobility has been directed by the state through strict control over educational opportunities. Preference in admission to higher education has been given to children of peasants and workers, children of long-standing party members and children of persons killed in the resistance against the Germans in World War II (see ch. 6). The political orientation of the student himself and his membership in mass organizations such as the youth union are also important factors in determining his admission to an institution of higher learning.