This project will explore the effects of two environmental factors – socioeconomic status(SES) and multilingualism – on children’s cognitive development. This line of research isimportance as it represents a crucial step in the development of specific intervention andprevention programs for young children who are at risk for school failure. Increasing evidence ofbrain plasticity in response to experience throughout development indicates that effects of earlyenriched or deprived environments on cognitive development are plausible. From thisperspective, growing up in underprivileged socioeconomic conditions might constitute a seriousrisk factor for children’s cognitive development as the degree of cognitive stimulations has beenfound to be considerably affected by lack of income. Growing up as a bi- or trilingual in amultilingual society, in contrast, might have beneficial effects on children’s early cognitivefunctioning, potentially via the opportunity it provides to “train” specific cognitive functions byinhibiting one language when using another and flexibility switching between languages.Debate exists over the degree to which SES and multilingualism affect areas of cognition. Thepresent project will explore these two environmental factors in children from various groups,differing in SES, culture, and language background. More particularly, the study will focus onthe impact of SES and multilingualism on two specific cognitive domains – language andexecutive functioning – that have been shown to have close links with children’s educationalprogress and later success in life. The main goal of this research is to characterize theneurocognitive profile of SES and multilingualism in terms of strengths and weaknesses inspecific cognitive systems. A battery of task tapping three different areas of executive functions(working memory, inhibition, and switching) and two domains of language (lexicon and syntax)will be administered to a large population of 7- and 9-year-olds. Children will be drawn from 7different language groups: secondary language learners, Portuguese immigrant children, andbalanced bilinguals from Luxembourg, monolingual children from Germany and Portugal, andmonolinguals of high and low SES from Brazil. The hypotheses to be tested will address,among others, whether or not SES and multilingualism account for group differences in theneurocognitive systems listed, including a finer-grained analysis of cognitive functions than wascarried out by previous studies in the domain.The presented study is the first of its kind to address these research questions in a largepopulation if multilingual children. Previous studies in the domain have almost exclusivelyfocused on monolingual English speaking children or a single bilingual group. Furthermore, thestudy is unique in considering both multilingualism and SES in the same research project.Appropriately describing a phenomenon is a crucial step in understanding it. A scientificallybasedexploration of the potential links between SES, multilingualism, and cognitiveachievement is therefore of the utmost importance as it is the necessary prerequisite for thedesign of interventions, with educational strategies targeted at cognitive outcomes and socialstrategies targeted at underlying mediating factors.