The focus of this volume is on the relation between synchrony and diachrony. It is examined in the light of the most recent theories of language change and linguistic variation. What has traditionally been treated as a dichotomy is now seen rather in terms of a dynamic interface. The contributions to this volume aim at exploring the most adequate tools to describe and understand the manifestations of this dynamic interface. Thorough analyses are offered on hot topics of the current linguistic debate, which are all involved in the analysis of the synchrony-diachrony interface: gradualness of change, synchronic variation and gradience, constructional approaches to grammaticalization, the role of contact-induced transfer in language change, analogy. Case studies are discussed from a variety of languages and dialects including English, Welsh, Latin, Italian and Italian dialects, Dutch, Swedish, German and German dialects, Hungarian.