Valence alternations, i.e. the use of a given verb in different syntactic patterns, are a well-studied topic in contemporary linguistics. The present book is dedicated to the diachronic development of such valence alternations: How do new ways of encoding valence alternations emerge? How do they spread and why do they spread? And what are the consequences of their emergence and spread for already existing patterns? This book discusses these questions on the basis of a concrete example of valence alternation, namely the French causative-anticausative alternation.