The aim of this book is to examine transcategorial shift between the nominal and verbal classes and develop a theoretical model to measure the relation between diachronic changes in a construction's degree of morphosyntactic categoriality and its degree of functional-semantic categoriality. This model is operationalized by applying it to the analysis of the English gerundive system, a network of related constructions that exhibit varying degrees of categorial hybridity. The volume is thus an excellent read for everyone interested in cognitive-functional linguistics in general, and diachronic linguistics in particular.