This project focuses on two endangered languages in different modalities: Catalan Sign Language (LSC, Catalonia) and Griko (Italiot- Greek variety of Salento, Southern Italy). Change in morphosyntactic properties within such languages has received very little attention so far. This project will make a novel contribution to fill this gap in research from a cross-modal perspective on two fronts: (a) exploring how diachronic change in a relatively small time span can be detected, described and accounted for (microdiachrony), and (b) creating research resources in the form of two corpora that include transcribed and annotated data to make the study of grammatical change feasible.