As we launch the ninth edition of Pathologic Basis of Disease we look to the future of pathology as a discipline and how this textbook can remain most useful to readers in the twenty-first century. It is obvious that an understanding of disease mechanisms is based more than ever on a strong foundation of basic science. We have always woven the relevant basic cell and molecular biology into the sections on pathophysiology in various chapters. In this edition we go one step further and introduce a new chapter at the very beginning of the book titled “The Cell as a Unit of Health and Disease.” In this chapter we have attempted to encapsulate aspects of cell and molecular biology that we believe are helpful in preparing readers for the more detailed discussions of specific diseases. We would like to remind readers that the last time a new chapter was added to this book was in 1967 when Stanley Robbins, at that time the sole author, decided to add a chapter on genetic diseases, one of many farsighted decisions by Dr. Robbins. We hope that the new chapter will be in keeping with his legacy. In the preface of the very first edition (1957), Stanley Robbins wrote: “The pathologist is interested not only in the recognition of structural alterations, but also in their significance, i.e., the effects of these changes on cellular and tissue function and ultimately the effect of these changes on the patient. It is not a discipline isolated from the living patient, but rather a basic approach to a better understanding of disease and therefore a foundation of sound clinical medicine.”