Many theories hold that language change, at least on a local level, is driven by a need for improvement. The present volume explores to what extent this assumption holds true, and whether there is a particular type of language change that we dub language change for the worse, i.e., change with a worsening effect that cannot be explained away as a side-effect of improvement in some other area of the linguistic system. The chapters of the volume, written by leading junior and senior scholars, combine expertise in diachronic and historical linguistics, typology, and formal modelling. They focus on different aspects of grammar (phonology, morphosyntax, semantics) in a variety of language families (Germanic, Romance, Austronesian, Bantu, Jê-Kaingang, Wu Chinese, Greek, Albanian, Altaic, Indo-Aryan, and languages of the Caucasus). The volume contributes to ongoing theoretical debates and discussions between linguists with different theoretical orientations.