This is the first book that discusses the effect of foreign language learning on first language processing. The authors argue that multilingual development is a dynamic and cumulative process characterized by transfer of different nature, and results in a common underlying conceptual base with two or more language channels that constantly interact with each other. Language representation and processing are discussed from a cognitive-pragmatic rather than a lexical-syntactic perspective. This required the review of several crucial issues of L2 acquisition, such as transfer, vocabulary development, conceptual fluency, and pragmatic skills. The authors also reviewed a large body of literature touching on cognitive psychology, linguistics, psycholinguistics, SLA, philosophy, and education in order to explain multilingual development and the positive effect of foreign language learning on the first language. An important read for linguists and language educators alike, this volume: * attempts to explain multilingual development from a cognitive-pragmatic perspective, * argues that foreign language learning has a positive effect on the development and use of mother tongue skills, * relies on research findings of several different disciplines, * builds on the results of quantitative research conducted by the authors, and touches on a wide range of literature.