In Grammaticalising the Perfect and Explanations of Language Change: Have- and Be-Perfects in the History and Structure of English and Bulgarian, Bozhil Hristov investigates key aspects of the verbal systems of two distantly related Indo-European languages, highlighting similarities as well as crucial differences between them and seeking a unified approach. The book reassesses some long-held notions and functionalist assumptions and shines the spotlight on certain areas that have received less attention, such as the role of ambiguity in actual usage. The detailed analysis of rich, contextualised material from a selection of texts dovetails with large-scale corpus studies, complementing their findings and enhancing our understanding of the phenomena. This monograph thus presents a happy marriage of traditional philological techniques and recent advances in theoretical linguistics and corpus work.