"Those who have stayed with Tom and me through the previous editions of Principles of Biomedical Ethics have earned our deep gratitude for their critical and constructive suggestions. These contributions provided a constant source of information, insight, and inspiration. Substantial changes have appeared in all editions after the first, and this ninth, and final, edition is no exception. The book's basic structure has not changed from the eighth edition, but revisions and expansions occur throughout the text. These reflect attempts to sharpen investigations, strengthen arguments, address issues raised by critics, and both reference and assess new published material. As in previous editions, changes appear in most sections and subsections of the book's ten chapters, along the lines indicated in the plan above. Following is a summary of major clarifications, additions, expansions, and responses to critics in this edition: Part I, Moral Foundations: Chapter 1, "Moral Norms," clarifies, augments, and further tightens our account of the common, universal morality, as distinguished from particular moralities, including professional moralities, and delineates their relations. This chapter and Chapter 10 further clarify the ways in which the four-principles framework, along with specified and derivative rules, is to be understood as a substantive framework of practical normative principles and a method of bioethics. This chapter also indicates how our framework addresses disagreements and conflicts, for instance, about COVID-19 vaccine mandates for admission to organ transplant wait lists, and how the framework can illuminate ethical issues in developing technologies, such as artificial intelligence (AI) in medicine, including breast imaging, as well as more generally. This chapter also considers whether AI can be helpful in applying ethical principles, as some propose. A major commitment to the virtues and to moral character has also been evident in every edition of PBE. Chapters 2 and 9 clarify and expand our discussion of the nature and importance of moral virtues, moral ideals, and moral excellence. We give increased attention to role-related virtues, trusting relations, moral distress, and clinicians' conscientious objection, as well as whether there is a professional duty or only an ideal to treat patients with HIV/AIDS, COVID-19, and other infectious diseases in risky situations. We also examine living-donor kidney transplantation in light of these categories, particularly through several narratives"--