Book excerpt: This volume on grammaticalization focuses on new theoretical and methodological challenges underpinning language change. It provides new approaches and insights deepening our understanding of the cognitive, pragmatic, and socio-cultural mechanisms that trigger the formation and the change of grammars. In this volume, grammaticalization is dealt with diachronically, synchronically and as a by-product of dialogic interaction. Another key feature of this book is language diversity; as it includes studies on language families ranging from Niger-Congo, Koreanic, Japonic, Sino-Tibetan to Germanic and Romance. The novel aspects of grammaticalization addressed are new slants on the fundamental debate about grammaticalization as expansion vs reduction; the grammatical formation of ideophones; the semantic domain of fear as a source and a trigger of grammatical change, and many other aspects of semantic and morphosyntactic development.