This volume contains some important studies on syntax of Indo-European languages presented at the Delbrück Symposium on Indo-European Syntax on the occasion of the 100th anniversary of Berthold Delbrück's death in 2022. The book, which can be considered one of the results of a research project of a Marie Skłodowska-Curie European Fellowship (Università degli Studi di Verona), provides an overview of the current state of research on diachronic and historical syntax within Indo-European studies and highlights the changing legacy of a great researcher within specific language branches and syntactic categories.