This book traces the development of Greek from Proto-Indo-European to around the 5th century BC, drawing on all the tools of scientific historical and comparative linguistics. Don Ringe begins by outlining the grammar of Proto-Indo-European, focusing on its complex phonology, phonological rules, and inflectional morphology. He then discusses the changes in both phonology and inflectional morphology that took place in the development of Greek up to the point at which the dialects began to diverge, seeking to establish chronological relationships between those changes. The book places particular emphasis on the diversification of Greek into the attested groups of dialects, the relationship between those dialects, and the extent to which innovations spread across dialect boundaries. The final two chapters cover syntactic changes in the prehistory and history of Ancient Greek, and the sources of the Ancient Greek lexicon. The volume contributes to long-standing debates surrounding the classification of Ancient Greek dialects, and offers a discussion of the tension between cladistics and contact phenomena that is relevant to the study of the relationships within any language family.