This book offers a comprehensive account of Arabicization in the Middle East and Egypt in the early period of the Arab conquests. Drawing on material from ancient Arabic grammarians as well as modern studies in second language acquisition, it analyzes the linguistic and non-linguistic ecological factors that contributed to the development of Arabic during the early period after the Arab conquests. It describes the pre-Islamic linguistic and sociolinguistic situation and traces the development in this period. The sociological, cultural, and sociolinguistic context is sketched to determine the nature and quality of the process of learning Arabic in the early period. The work further discusses the process of learning Arabic as a second language and the input provided by the native speakers, which both affected the structure of the emerging dialects.