The relevance of this book is highlighted first by the fact that language-based approaches are still lacking in Arabic dialectology. The classification of Arabic dialects is not yet entirely satisfactory. Geographical and sociological layers were traditionally based on the assumption that the saliency of some features in the Modern Arabic dialects is the product of two different processes: diffusion and innovation. However, this traditional approach is not consistent with the history of Arabic. For instance, the saliency of some features that support the classification of the Modern dialects varies according to features that can be traced back to Classical Arabic, Islamic dialects, Old Arabic dialects, or proto-Arabic. Another explicative process has been, to some extent, neglected in the study of Arabic dialects, namely inheritance. Some phonological features currently present in Modern Arabic dialects cannot be explained by any of the two terms of this paradigm. As long as the mapping of Western approaches on Arabic dialects seems to be relatively unsatisfactory, diffusion and innovation are found to be incomplete to explain the extreme variability of the linguistic features of the Arabic dialects. Since some features appear in very distant isolated isoglosses, they are consistent neither with diffusion nor with concomitant innovation; only their underlyingly inherited nature could provide a logical scheme. Introducing the process of inheritance, besides diffusion and innovation, aims to enlarge our knowledge of the history of the Modern Arabic dialects. The threefold paradigm is more accurate to perform satisfying explanations of the features of similarity and dissimilarity between Old Arabic and Modern Arabic dialects, at the synchronic and diachronic levels. This book aims to shed light on recent trends in Arabic dialectology. Cross-cultural analyses are provided by scholars from different origins (Arabic native speakers and excellent Arabists) and from different linguistic backgrounds (Arabic, Berber, English, French, Hebrew, Spanish). The chapters are all devoted to produce systematic descriptions and analyses of Arabic dialects. The book is divided into three thematic sections: (a) Theoretical and Historical Perspectives and Methods in Arabic Dialectology; (b) Eastern Arabic Dialects; and (c) Western Arabic Dialects.