The research programme on multilingualism focuses on how human beings acquire and use more than one language and how proficient they become as multilingual speakers. Focus : In this newly developed programme there are two areas of special interest. The sub-programme on second language acquisition studies second language development and proficiency from both a structural and a cognitive point of view, in direct relation to the impact of the first language. The aim is to explain the construction and architecture of a second language and its dependency on properties of the first language and/or cognitive structures or preferences. The second sub-programme, on bilingual usage and processing, studies the direct interaction between languages or language varieties in their actual use and the way these languages are processed. The aim is to explain how different languages can compete and/or cooperate in language use and in language processing and how this helps us to understand the basic structures in human language and cognition. To achieve this aim, various multilingual populations will be studied, with various L1 and L2 backgrounds, and with various proficiency levels. Research on bi- or multilingualism is embedded in a wider Nijmegen context in which the study of bilingualism is carried out in a multidisciplinary perspective. The other partners are the Max Planck Institute of Psycholinguistics, the Nijmegen Institute on Cognition and Information, the Institute for Behavioural Science, and the F.C. Donders Institute (Neuroscience). Research on bilingualism has won a prominent place on the (inter)national research agenda in the last two decades. New journals have started, new international conference series have emerged, and special research funds have become available (cf. the programme on Multilingualism and Language Acquisition of the Dutch national research organisation NWO, in which Nijmegen acquired two research projects). From a societal point of view, knowledge on multilingual development and proficiency is a topic with a wide and profound impact. Worldwide communication today is dominated by bilinguals and the European language policy is based on the concept of European citizens speaking more than one language. On the national level, each year billions of euros are invested in secondary schools to teach pupils to speak more languages. The role of databases has grown significantly in the field of multilingualism and language acquisition. The research programme on multilingualism includes a special project on bilingual databases, in cooperation with the Max Planck Institute, the Meertens Institute, and Tilburg University. The line of developing and exploiting data resources will be continued, including the (meta)analysis of (longitudinal) databases on school achievements and language proficiency which have become available in the Dutch research context over the past years.