Donald D. Clayton’s Principles of Stellar Evolution and Nucleosynthesis remains the standard work on the subject, a popular textbook for students in astronomy and astrophysics and a rich sourcebook for researchers. The basic principles of physics as they apply to the origin and evolution of stars and physical processes of the stellar interior are thoroughly and systematically set out. Clayton’s new preface, which includes commentary and selected references to the recent literature, reviews the most important research carried out since the book’s original publication in 1968.