The project INSPIRE (multilINgual Sentence Processing In Real-timE) will investigate two potential factors that influence multilingual sentence processing, cross-linguistic influence and language dominance, to shed light on the ongoing debate about how the language systems in a multilingual speaker's mind/brain interact. We will employ two time-sensitive methods, eye-tracking and mouse-tracking, to investigate how German native speakers living in Norway and non-native speakers of German whose native language is Norwegian process German case marking in different sentence structures (transitive structures, ditransitive structures); the findings will be compared to those obtained from a group of German native speakers in Germany. The language combination was chosen because it enables us to test whether the groups differ in how they use morphological case and word order to identify who did what to whom in a sentence. Unlike German, Norwegian has no morphological case on full noun phrases, but mostly relies on word order for sentence interpretation. Our experimental design not only enables us to investigate whether non-native speakers are affected by cross-linguistic influence from their first language (Norwegian) when processing German (and rely more on word order than case), but also how a change in language dominance affects sentence processing in German native speakers, i.e., whether they show a processing pattern that is more similar to that of the non-native group after longer exposure to and usage of Norwegian. Thus, unlike previous studies, INSPIRE will reveal whether cross-linguistic influence is bidirectional. The project will fill a gap in current research on language attrition by investigating real-time processing and will inform us how the lack of input and use can affect the processing of the first language. INSPIRE addresses aspects that are relevant for all who have to deal with multilingualism in their daily life (e.g., language therapists and teachers).