The Research Unit Emerging Grammars (RUEG) investigates the linguistic systems and linguistic resources of bilingual speakers from families with an immigrant history, “heritage speakers”, in both of their languages across different language pairs, registers, and age groups. We investigate speakers of Russian, Turkish, and Greek as heritage languages in Germany and the U.S., in addition to German as a heritage language in the U.S., as well as monolingual controls for majority and heritage languages. We study noncanonical phenomena as indicators of new grammatical options in bilingual systems. All projects contribute to three “Joint Ventures” targeting (1) the development of new dialects vs. incomplete acquisition or erosion (“Language Change Hypothesis”), (2) the relevance of internal vs. external grammatical interfaces (“Interface Hypothesis”), and (3) the distinction of contact-induced change vs. language-internal developments and variation (“Internal Dynamics Hypothesis”). As a result of our collaborative research, we expect new insights into the special dynamics of language variation, language change and linguistic repertoires in contact situations and the modelling of noncanonical structures in the grammatical system, and new impulses for the investigation of heritage speakers and of speakers’ resources. The projects are supported by two Mercator Fellows: Shana Poplack, University of Ottawa Maria Polinsky, University of Maryland The Research Unit is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project number: 39482131. You can search this data online in ANNIS: https://korpling.german.hu-berlin.de/annis3/#c=rueg