This volume presents the first truly systematic, multi-disciplinary, and cross-linguistic study of the language and writing system factors affecting the emergence of dyslexia. Bringing together a team of scholars from a wide variety of disciplines, it takes a dual focus on the language-specific properties of dyslexia and on its core components across languages and orthographies, to challenge theories on the nature, identification and prevalence of dyslexia, and to reveal new insights. Part I highlights the nature, identification and prevalence of dyslexia across multiple languages including English, French, Dutch, Czech and Slovakian, Finnish, Arabic, Hebrew, Japanese and Chinese, while Part II takes a cross-linguistic stance on topics such as the nature of dyslexia, the universals that determine relevant precursor measures, competing hypotheses of brain-based deficits, modelling outcomes, etiologies, and intergenerational gene-environment interactions.