Whenever we speak in a particular language variety rather than another, we display an affinity with one social group distancing ourselves from other social groups. The identity–marking function of speech is as important as the communicative one. The type of language variety, people use, makes a considerable contribution to shape their social identities. This means that the people with high social or political status should often carefully control their language styles in order to exert profound influence on people's attitudes to meet desired expectations. In fact, social class-based language differences may have more important social implications than regional variations. In many class-conscious societies, particular varieties associated with lower social classes, may be greatly stigmatized by the members of the society. Hence, the speakers of less prestigious varieties may often lose many educational and occupational opportunities unfairly. However, a language variety in linguistic term is more expressive, logical, regular, and correct than social varieties. Therefore, making any valid judgment on the superiority or inferiority of a particular language variety is concerned with social and political affairs and does not have any linguistic merits. The article also discusses the relation between language variety and cognitive ability of language users based on Bernstein’s theory and the critics. © 2015, Canadian Center of Science and Education. All right reserved.