"With the European Union, a growing group of children learns how to read in two languages at the same time. Interestingly, the Basque language is used in Spanish and French regions of Europe and many children must learn to read in Basque in parallel to either an opaque (French) or a shallow (Spanish) orthography. This project investigates the foundations of bilingual reading acquisition, taking into account the features of the languages learned. It has been shown that the chunk size of letter strings processing depends on grapheme-to-phoneme conversion rules’ regularity, defining the extent to which decoding and lexical reading strategies are taxed. Few studies have focused on bilingualism impact on reading strategies and disorders. Yet, reading difficulties occur also in bilinguals and adapted diagnostic and remediation tools for this population are needed. Performance of Basque-Spanish and Basque-French bilinguals attending Basque-medium schools in Grade 2 and Grade 5 will be assessed on Basque reading, related cognitive skills and their electrophysiological markers. Taking into account the transparency of the second language learned, the present study aims at identifying differences in developmental time course of reading acquisition and in manifestations of reading disorders in Basque. Because the tests given will be identical for the two bilingual groups, i.e., in Basque, data will bring evidence missing in previous cross-linguistic studies to identify cognitive predictors and cerebral markers of normal and impaired reading acquisition in regular and irregular orthographies. Such cross-sectional study will enable to determine to what extent linguistic features positively or negatively impact on reading development. Importantly, the study will have concrete outcomes such as normative data to assess literacy in Basque, offering the opportunity to design adapted diagnostic and remediation tools for Basque literacy disorders in French and Spanish regions of Europe."