Lessons 1-7 introduce the range of Arabic diversity, from Old Arabic to modern dialects. Phonetic/phonological, morphological, syntactic and lexical features of different spoken varieties are presented by means of recorded and transcribed texts. The course continues with cross-dialectal comparison - developed around phonetic, morphological and lexical key issues. Current dialectal classifications - distinguishing eastern/western, urban/rural/Bedouin and communal varieties – are described using concepts of ‘linguistic classification’ and ‘reconstruction’, ‘areal vs. genetic feature’, ‘grammaticalization’, ‘shared innovation’ and ‘isogloss’. We will discuss theoretical and methodological issues: the strict correlation between linguistic variation and other social variables (ethnicity, urbanization and religion) supports the importance of integrating sociolinguistic approach and neo-grammarian models of reconstruction and classification: ‘sub-stratum’ and ‘Arabization’ become central for historical reconstruction, to situate Arabic dialects within Semitic.