A generation ago, we adopted a national system for the protection of human subjects in research. Today, that system is facing new challenges. Many argue that the system has failed to evolve in concert with dramatic changes in the research environment. Accordingly, efforts are underway to reform the existing process to make it both more efficient and more effective. At the same time, many are also reexamining the system in more fundamental ways — going well beyond considerations of policies and compliance and raising questions that go to the very foundations of what constitutes an ethical conduct of human research.Experimentation involving human subjects is a necessary step in the process of translating scientific discovery and technological advancement into procedures and products that offer the prospect of better lives for all of us. It helps us to better understand why we do the things we do and believe what we believe.