Previous research in first (L1) and second language (L2) acquisition has provided evidence that linguistic confidence is a key construct that can explain linguistic behaviour. In this paper, we apply previous research in the socio-contextual model of L2 learning to data from Catalonia. More specifically, the paper investigates linguistic confidence towards Catalan and Spanish by students in Catalonia for a period of 5 years, that is, from their last year of primary education to their last year of secondary education. The methodology for the longitudinal study was based on a survey on linguistic confidence in Catalan and Spanish and other sociolinguistic and demographic information by students in five different locations in Catalonia. The results of the study show evidence that (a) linguistic confidence is very high for Catalan and Spanish; (b) there is a relationship between confidence in Spanish and Catalan and the students' L1; and (c) over time linguistic confidence in both languages increases. These results are discussed in light of current discussions on the stable or dynamic nature of linguistic confidence.