The present thesis provides an analysis of language policy and language contact in present-day Barcelona. On the one hand, the effectiveness of the implementation of Catalan-medium education in Catalonia will be critically evaluated. On the other hand, Catalan-Castilian bilinguals' awareness of non-normative instances of language contact will be assessed. This thesis brings these two strands together, in order to paint an accurate picture of the current Catalan sociolinguistic situation. The 1983 Llei de Normalització Lingüística had numerous consequences, including the introduction of Catalan as the chief medium of education in Catalonia. Such legislation had many aims, not least to 'ensure Catalan language competence'. But to what extent has this been successful? Furthermore, the varieties of Catalan and Castilian in Barcelona are characterised by centuries of language contact, which has resulted in the incursion of numerous, non-normative linguistic items and constructions in both languages. To what extent are speakers aware of such non-normative language? Moreover, how do these questions concerning language policy and language contact bear upon one another? This thesis is therefore looking at the consequences of language policy and of language contact. With the aid of an innovative, three-dimensional model of sociolinguistic phenomena, it will be shown that these are maximally differentiated, yet clearly related. These will be termed top-down phenomena and bottom-up phenomena respectively. This is to be tested using a unique fieldwork experiment whereby fifty bilingual Catalan-Castilian Barcelonians of two different generations (one educated in Catalan, the other in Castilian, due to different linguistic policies) are asked to identify instances of non-normative language contact in two prepared texts. This work will allow conclusions to be drawn regarding the effectiveness of Catalan medium education, as well as offering insight into the nature of how we examine issues of language policy and language contact.