As the fourth instalment of "Amsterdam Studies in the Theory and History of Linguistic Science", Keys to the History of English: Diachronic Linguistic Change, Morphosyntax and Lexicography (Porck et al., 2024) comprises papers presented at the 21st International Conference on English Historical Linguistics (ICEHL) held in 2021 at Leiden. The publication covers three core themes: diachronic language change, morphosyntax, and lexicography. The volume adopts a macro perspective on the diachronic development of language, synthesizing detailed analyses of historical texts with contemporary corpora and experimental methods. The present volume represents a significant contribution to the field of historical linguistics, offering new insights into the evolution of the English language. It emphasizes the importance of a comprehensive understanding of English historical linguistics for linguistic research.