The diachrony of classification systems provides a novel diachronic approach to studies in classification systems by presenting data of a wide genetic and typological diversity. This approach connects with the theme of Linguistic Variation by investigating language-particular versus language-universal properties in the diachrony of classification systems intra- and inter-linguistically. The book includes discussion on languages from various families (Oceanic, Indo-European, Niger-Congo, Australian) and geographical areas (Araxes-Iran, Southwestern Amazonia, Southeast Asia). Different types of classification systems are studied, including numeral classifiers, possessive classifiers, and verbal classifiers, among others. Different methods are also used to carry out the investigations, e.g., corpus study, history of linguistic descriptions, and historical reconstruction. This book is thus an appropriate source for linguists that are already working on a specific topic related to classification systems to expand their knowledge on other types of classification systems. The book consists of ten chapters written by different contributors. Six of them were presented in the workshop The diachrony of classification systems organized in the Netherlands in 2009, and four others were solicited to increase the geographical and genetic coverage of the discussion.