This volume contains 21 new and original contributions to the study of formal semantics, written by distinguished experts in response to landmark papers in the field. The chapters make the target articles more accessible by providing background, modernizing the notation, providing critical commentary, explaining the afterlife of the proposals, and offering a useful bibliography for further study. The chapters were commissioned by the series editors to mark the 100th volume in the book series Studies in Linguistics and Philosophy. The target articles are amongst the most widely read and cited papers up to the end of the 20th century, and cover most of the important subfields of formal semantics. The authors are all prominent researchers in the field, making this volume a valuable addition to the literature for researchers, students, and teachers of formal semantics. Chapter 19 is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.