Since the late 19th century, state legislatures and professional medical organizations have developed mechanisms to license physicians and other conventional nonphysician providers, establish standards of practice, and protect health care consumers by establishing standardized credentials as markers of competence. The popularity of complementary and alternative medical (CAM) therapies presents new challenges. This article describes the current status of, and central issues in, efforts to create models for health care credentialing of chiropractors, acupuncturists, naturopaths, massage therapists, and other CAM practitioners. It also suggests a strategy of CAM provider credentialing for use by physicians, health care administrators, insurance companies, and national professional organizations. The credentialing debate reflects fundamental questions about who determines which providers and therapies will be accepted as safe, effective, appropriate, and reimbursable. More nationally uniform credentialing mechanisms are necessary to ensure high standards of care and more generalizable clinical research. However, the result of more uniform licensure and credentialing may be excessive standardization and a decrease in individualization of services. Thus, increased standardization of credentialing for CAM practitioners may alter CAM practice substantially. Furthermore, even credentialed providers can deliver ineffective therapy. The suggested framework balances the desire to protect the public from dangerous practices against the wish to grant patients access to reasonably safe and effective therapies.