Forceful new demands for accountability in medicine are arising from many interested parties. To maintain professional standards, physicians need to establish which demands are desirable and which are not. We adopt a model of stratified accountability that includes three major components: the accountable parties, the subject matter, and the processes for accountability. To begin describing the model, we focus on physicians and health care institutions. We focus on the ethical dimensions of medical practice, both because the difficulty of measuring such behaviors makes this a test case for accountability and because of the importance of ethical standards in maintaining patient trust. We first identify eight widely endorsed content areas for accountability in ethical conduct: medical decision making, confidentiality, fiduciary obligations (including conflicts of interest), responsibilities arising from patient vulnerability, personal standards, equity among patients, cultural representation, and procedures for resolving dilemmas. We then identify the currently most valid and reliable methods for assessing conduct: surveys among all involved parties, testing methods used for accreditation, limited audits, publication of policy, and careful use of report cards. A prototypical survey and report card are illustrated. However, we also note the need for improved accountability assessment methods. We next identify mechanisms for taking responsibility: sharing information, exchanging perspectives, making adjustments, and enforcing standards when necessary. Finally, because this report only begins to describe a small part of the accountability model, we urge explicit identification and development of professional standards for accountability in the many other areas of medicine.