This thesis explores the nature and the mechanism of change of language prestige and language attitudes in two neighbouring languages: Occitan and Catalan. These two Romance minority languages show great similarities in their early external history and striking differences in their more recent past. The concepts of language attitudes and prestige call for a multidisciplinary approach which incorporates aspects from social psychology, ethnography, historical sociolinguistics and sociology to enable the author to depict in a comprehensive manner the interaction between the formation of the perception of language prestige and the declaration of language attitudes.An important rationale in this thesis is the search for an understanding of the patterns of change in prestige descriptions. Prestige and attitudes are generally interpreted as static entities but a diachronic overview of the values attached to Catalan and Occitan displays signs of disparity and evolution which are scrutinised through the analysis of selected Occitan and Catalan grammars from different periods. The data collected through semi-structured interviews with Occitan and Catalan speakers and processed with the method of Critical Discourse Analysis provides an enlightening synchronic perspective on the language situations. The combination of diachronic and present-day approaches to language representations fosters an original apparatus to investigate the gradually developing contrasts between the symbolisation of the two languages. A second point of focus for the comparison of the Occitan and Catalan linguistic situations resides in the transnational position of their linguistic communities. Since Occitan and Catalan are both spoken in France and Spain, the fascinating mismatch between the linguistic borders and the political territories provide an original and supplementary instrument of analysis of the influences of the national policies on individual attitudes. The bi-national division of Catalan and Occitan offers an examination of the inter-relation between macro-level representations and micro-level perceptions and a clarification of the dynamicity of the power relations between minority and majority groups.The objective of the study is primarily to contribute to a theorisation of language prestige through its conceptualisation as a process, and not an inherent quality, influencing, renewing or destroying, positive language attitudes which, in turn, can reinforce or challenge the preconceived and established form of prestige. The dynamic and malleable forms of prestige and attitudes need the explanatory help of the concept of language ideologies which, taken as beliefs about a language, embodies the modern and growing differentiation in the attribution of language values to Catalan and Occitan. Language ideologies as well as constituting a link between the macro and micro-domains reflect the emblematic discrepancies between a growingly powerful and confrontational Catalan prestige and a compartmentalised and disunited Occitan prestige.