In addressing the ethical issues that arise in treating both pain and addiction, the author of this chapter has organized his presentation around: the history of medical ethics; theories and definitions; and the ethical challenges to providing clinical care. The theoretical underpinnings to ethical decision-making are important to providing the best possible outcome, and their evolution is described, from the Hippocratic Oath to current human subjects’ protection rules for clinical trials. The tension between patient autonomy and the physician’s obligation to protect is as high as that seen in parenthood, but commonly with even less control of the individuals involved. A framework is provided for examining clinical cases that aids in addressing such topics as treatment disagreement, confidentiality, informed consent, abandonment, pregnancy, and biases that may be seen with categorical treatment programs (e.g., abstinence-based, faith-based). A text box is added giving additional resources on the topics discussed.