Contrary to most traditional approaches, ideologies are defined here within a multidisciplinary framework that combines a social, cognitive and discursive component. As ‘systems of ideas’, ideologies are sociocognitively defined as shared representations of social groups, and more specifically as the ‘axiomatic’ principles of such representations. As the basis of a social group's self-image, ideologies organize its identity, actions, aims, norms and values, and resources as well as its relations to other social groups. Ideologies are distinct from the sociocognitive basis of broader cultural communities, within which different ideological groups share fundamental beliefs such as their cultural knowledge. Ideologies are expressed and generally reproduced in the social practices of their members, and more particularly acquired, confirmed, changed and perpetuated through discourse. Although general properties of language and discourse are not, as such, ideologically marked, systematic discourse analysis offers powerful methods to study the structures and functions of ‘underlying’ ideologies. The ideological polarization between ingroups and outgroups— a prominent feature of the structure of ideologies—may also be systematically studied at all levels of text and talk, e.g. by analysing how members of ingroups typically emphasize their own good deeds and properties and the bad ones of the outgroup, and mitigate or deny their own bad ones and the good ones of the outgroup.