This article discusses the effectiveness of Participatory Action Research-PAR to foster linguistic mudas, transformative processes among young new speakers of Basque leading to linguistic mudas (Pujolar and Gonzàlez. 2013. "Linguistic Mudes and the Deethnicization of Language Choice in Catalonia." "International Journal of Bilingual Education and Bilingualism" 16 (2): 138-152) in favour of the minority language. Taking into account the three principles of PAR --research, participation, and action--, and using an ethnographic action-based approach, participants in the research project were agents of their own linguistic change by becoming co-researchers, who observed their own behaviour and set themselves personal challenges for increasing their everyday use of Basque. We describe how participants engaged in a process of self-awareness and reflective thinking in which teamwork, cooperative discussion of ideas and experiences, and relations of accompaniment (Bucholtz, Casillas, and Lee. 2016. "Beyond Empowerment: Accompaniment and Sociolinguistic Justice in a Youth Research Program." In "Sociolinguistic Research: Application and Impact," edited by R. Lawson, and D. Sayers. Routledge) proved crucial to find strategies for increasing new speakers' control and agency (Ahearn 2001. "Language and Agency". "Annual Review of Anthropology" 30: 109-137.), in order to enact the changes they desired. The article shows PAR methodology to be effective to bring about a change in participants' subjectivities and linguistic practices, as well as to understand the complexities of muda processes among Basque new speakers in dominantly Spanish-speaking sociolinguistic contexts.