This project studies the development of socially meaningful language variation in (pre)adolescents with Down Syndrome (hence ‘DS’). ‘Socially meaningful language variation’ can be observed when two or more variants denote the same concept, but each of these variants conveys different social meaning about the speaker, the hearer, and the setting in which the variant occurs (Labov, 1972). To illustrate, a Belgian Dutch (hence ‘BD’) speaker might prefer to address their doctor with the variant ‘u’ rather than the variants ‘je’ or ‘ge’ because they consider it the most appropriate in the formal context of a doctor’s visit. Such BD pronouns of address (including ‘u’, ‘je’, and ‘ge’) are employed as a case study in this project, since they show socially meaningful language variation on two dimensions: On the first dimension, they range from more to less formal, and on the second dimension, they range from standard to colloquial (Plevoets et al., 2008). To obtain the best view into how the development of socially meaningful language variation is related to social functioning (e.g., socially engaging with others) and language processing (e.g., using certain grammatical structures while talking), the participants of this project are (pre)adolescents with DS. This is due to these individuals’ unique developmental profile: They have strengths in social functioning on the one hand (Næss et al., 2017), and challenges with language processing on the other (Abbeduto et al., 2020). Overall, this project aims to recruit 32 dyads, each consisting of a (pre)adolescent with DS and their caregiver. It will investigate (a) how (pre)adolescents with DS vary in their productions of Belgian Dutch pronouns of address (via spontaneous language samples and a “discourse completion” experiment where they complete utterances), (b) how they vary in their evaluations of Belgian Dutch pronouns of address (via a “speaker evaluation” experiment where they express their attitude towards ‘u’/’je’/ ‘gij’ use in specific contexts and utterances), (c) the role of the caregiver in their productions and evaluations, and (d) how the participants reflect upon the results specific to their dyad, via a semi-structured interview. In line with the United Nation’s slogan “Nothing about us without us”, the project employs a participatory research framework by including a focus group of (pre)adolescents with DS and their caregiver, a consultation board of persons professionally or privately involved with individuals with DS outside academia, and by involving the participants in the co-analysis of their results. The results are correlated with several measures of language processing and social functioning in the (pre)adolescents with DS to map out the development of socially meaningful language variation. This project contributes to our understanding of the social meaning in language and advances current knowledge in developmental sociolinguistics by adding a unique perspective to the discipline. Literature Abbeduto, L., Arias-Trejo, N., Thurman, A. J., Ramos-Sanchez, J., & del Hoyo Soriano, L. (2020). Language Development in Down Syndrome. In J. A. Burack, J. O. Edgin, & L. Abbeduto (Eds.), The Oxford Handbook of Down Syndrome and Development. Oxford University Press. https://doi.org/10.1093/oxfordhb/9780190645441.013.18 Fidler, D. J., Most, D. E., Booth-LaForce, C., & Kelly, J. F. (2008). Emerging Social Strengths in Young Children With Down Syndrome. Infants & Young Children, 21(3), 207–220. https://doi.org/10.1097/01.IYC.0000324550.39446.1f Labov, W. (1972). Sociolinguistic patterns (11. print). Blackwell. Næss, K.-A. B., Nygaard, E., Ostad, J., Dolva, A.-S., & Lyster, S.-A. H. (2017). The profile of social functioning in children with Down syndrome. Disability and Rehabilitation, 39(13), 1320–1331. https://doi.org/10.1080/09638288.2016.1194901 Plevoets, K., Speelman, D., & Geeraerts, D. (2008). The distribution of T/V pronouns in Netherlandic and Belgian Dutch. In K. P. Schneider & A. Barron (Eds.), Variational pragmatics: A focus on regional varieties in pluricentric languages (pp. 181–210). John Benjamins.