In this book, the authors present research and theory to argue that metalinguistic awareness of one's native language is altered by either the acquisition or the learning of a second language. The main argument is that people with more than one language have different knowledge of their first language (L1) than do monolingual people, and this difference can mainly be due to the effect of subsequent languages on the development and use of L1 skills. This book offers: a multilingual perspective which emphasizes that knowledge of two or more languages results in a unique and complex competence that is not equal to the sum of knowledge of monolingual speakers of those languages; an attempt to demonstrate that effective language learning can lead to multicompetence even if socio-cultural background of the target language is not present; and a cognitive-pragmatic perspective of language representation and processing which means a move away from the lexical-syntactic approach that has been dominating bilingual research.