Mainland Scandinavian (MSc) marks a fascinating linguistic scenario: relying on mutual intelligibility, speakers use their native language (L1) when conversing with foreign MSc-interlocutors and keep doing so even if immersed in the target speech community for years. This raises the question if non-native speakers of a closely related target language (Ln) use different grammars or resort to the L1 grammar when processing the Ln, whether parsing it causes attrition, and if any of this is modulated by exposure. CloReLa (Closely Related Languages: Processing, Attrition and Exposure) addresses these issues by comparing processing and judgment data of native speakers of Norwegian and non-native speakers with L1 Swedish or Danish. To this end, we employ an innovative combination of on- and off-line methods: Eye-Tracking while Reading (ETR) and Acceptability Judgment Tasks (AJT), conducting in-person studies at UiT and collecting data from speakers in Sweden and Denmark via web-based surveys. Considering closely related languages serves to close important knowledge gaps: these exhibit a broader range of contrasts than dialects, no common standard to fall back on and a slowly deteriorating mutual intelligibility. Whether non-native speakers postulate dedicated rules and are more prone to attrition or not has extensive implications for models of the cognitive organisation of linguistic systems and factors affecting their formation. CloReLa emphasizes the potential of closely related varieties and sparks methodological advances by promoting a novel mix of methods to study (un)grammaticality in parsing. The action allows the PI to build on psycholinguistic and theoretical expertise and trains him in ETR and transferable skills, an ideal mix of training-through-research and formal training. In AcqVA Aurora, which excels in research on multilingualism, he will contribute to ongoing projects and take the lead on CloReLa to become a top-class linguist doing cutting-edge research.