Grammatical gender represents an important area of research given the difficulty gender assignment and agreement poses to bilinguals at all levels of proficiency. As such, the objective of GenBiLex is to develop a comprehensive proposal of grammatical gender in the bilingual lexicon that includes psycholinguistic, language acquisition and theoretical linguistic approaches. Little previous research has examined the consequences of differences between the L1 and L2 gender systems, either in terms of the number of gender values (e.g. 2 vs 3 values) or the values themselves (e.g. common/neuter vs masculine/feminine). GenBiLex addresses this crucial gap by examining bilinguals with different types of gender systems in order to offer insight into the representation of and interactions between the L1 and L2 gender features in the lexicon and how this is borne out in the use of gender in the L2. In this research 140 adult native speakers (L1) of Norwegian, German, Dutch and French learning Spanish (L2) perform an L2 gender decision task (indicate the gender value of L2 nouns) and an eye-tracking reading acceptability judgment task (rate sentences with code-switched Determiner Phrases, e.g. die mesa, ‘theGER tableSPA’). The stimuli are manipulated in terms of the gender congruency between the L1 and L2 nouns, allowing for the representation and use of gender in the L2 to be examined and bilinguals’ use of gender agreement in code-switching to be investigated with respect to theoretical syntactic proposals. GenBiLex complements previous work on grammatical gender by the Language Acquisition, Variation and Attrition group at the University of Tromsø, extending their research to include L2 acquisition and more language pairings. The outcome of this research will be a significantly deeper understanding of the representation and processing of grammatical gender in the bilingual lexicon that contributes to psycholinguistics, language acquisition and theoretical linguistics.