This article presents a longitudinal panel study analyzing the evolution of a sample of more than 1000 informants in the language practices with peers during the period between the end of primary education and the end of secondary education in Catalonia. Results led to the identification of five clusters of informants according to their linguistic trajectories. Three of them, which together accounted for 75% of all informants, combined the strong predominance of a single language--respectively Catalan, Castilian, and other languages--and a remarkable stability in patterns of language choice during the five years' period under scrutiny. The other 25% of informants, grouped in two different clusters, declared more bilingual/multilingual behavior and underwent more significant changes that may be related to "linguistic mudes" [Pujolar, Joan, and Isaac Gonzàlez. 2013. 'Linguistic "Mudes" and the Deethnicization of Language Choice in Catalonia.' "International Journal of Bilingual Education and Bilingualism"]. The study also explores the relevance of the transition between primary and secondary education as a social moment favorable for linguistic mudes and concludes that a small but still significant percentage of informants went through such changes in that transition.