This book is an introduction to professional ethics in chemistry. After a brief overview of ethical theory, it provides a detailed discussion of professional ethic for chemists based on the view that the specific codes of conduct derive from a moral ideal. The moral ideal presented here has three parts. The first refers to the practice of science, the second to relationships within the scientific community and the third to the relationship between science and society, particularly the uses of science. The question of why a scientist should obey the professional code is discussed in terms of the virtue of reverence, after which the ethical issues unique to chemistry are identified. A method for approaching ethical problems is presented. Finally, there is a large collection of specific ethical problems, or cases, each followed by a commentary where the issues raised by that case are discussed.