This small volume is designed to provoke thought about key question in modern research ethics. The result of a three-year collaboration between the nation’s two leading Catholic institutions devoted to medical ethics, The Catholic Medical Association and The National Catholic Bioethics Center, A Catholic Guide to Ethical Clinical Research attempts to resolve a series of real-life cases in research ethics by applying four key principles of the moral life, namely, truth, respect for life, the integrity of persons, and the conjoined ideas of generosity and justice. After a description of these principles, the authors turn to a remarkably wide range of cases on such diverse topics as informed consent, non-directed research, embryonic stem cells, in vitro fertilization, contraception, genetic modification, performance-enhancement, the selection of drugs for development, studies on poor or underprivileged populations, off-label use, and many other common cases in research ethics. The principles presented are true and certain, but the cases represent probable opinions. While the authors are certainly convinced of the merits of their own position, they resolve these cases in a manner that is designed to provoke the thoughtful reaction of the reader and so generate discussion. The main purpose of the volume is to show how principles should be applied to particular cases, thus providing a clinic in moral reasoning. To see and understand how the principles are applied in these particular cases should assist the reader in seeing how the same could be applied in other and perhaps very dissimilar cases. The opinions offered are the best-informed and most orthodox that could be expected from any assembly of Catholic scholars. Clinical research is a vitally important field of medicine that poses many moral challenges for the conscientious Catholic. This guide is a practical manual on how to think about the moral problems that confront the typical worker in the research setting today.