This volume is a collection of papers focusing on different aspects of clinical linguistics; it encompasses different issues on language pathologies, first and second language acquisition and impairments. In some cases, authors discuss clinical data concerning three major pathologies: agrammatism, the first research on which goes back to nineteenth century; Williams Syndrome deficit, a rare neurodevelopmental disorder; and Specific Language Impairment (SLI), a pathology whose controversial status with respect to linguistic and non linguistic explanations is widely debated in the literature. In other cases, the authors take into account various kinds of non-pathological topics whose relevance in clinical linguistics is well-known and crucial: the problems in the relationship of first and second language acquisition and the typologies of errors in non-pathological speech are discussed with respect to clinical linguistics data. Pathology (or disorder) must be defined with reference to normal function and a problem facing many research and clinical subspecialties is that what constitutes normal function is not well understood. The aim of this volume is to stress the growing importance of the theoretical and methodological linguistic tools developed in this area of interest; to discuss general problems raised by different analyses and to bring under scrutiny assumptions taken for granted in previous analyses, which may not be as obvious as they seem; to investigate how even apparently minimal choices in the description of phenomena may affect the form and complexity of the language/cognition interface. The research deals with two major areas of linguistics: aspects of phonetics and phonology, on the one hnd, and of syntax and semantics, on the other. The studies concern different language groups: Indo-European and Japanese. Among the languages of the former group, papers discuss data from Germanic languages (English and German), from Romance languages (Italian, Spanish and Venetian, a northern Italian Dialect) and from Persian. Moreover, one paper discusses data about one target language, English, but the categorial discrimination test proposed is used to assess the perception of English vowels by native speakers of Korean, Japanese, Czech, Hungarian, Arabic, Portuguese, German and Dutch. In another paper, a bilingual context, Italian and Venetian, is considered. Authors summarize their personal results by discussing subjects, materials, languages, scores, etc, but there is also space for a thorough discussion of the theoretical and empirical aspects of the most relevant literature. By focusing on empirical data about different languages, the interdisciplinary complexity of the language/cognition interface is explored. The relevance of linguistic theory in the development of clinical linguistics is also evaluated. The book is, therefore, not simply a series of scattered contributions to the field, but it offers a fairly comprehensive overview of the complexity of the field and of the linguistic implications for speech and language pathology. Problems discussed in this volume intend to fit into the contemporary research on Speech and Language pathology.