Marcia Angell is a senior lecturer in the Department of Social Medicine at Harvard Medical School and the former Executive Editor of the New England Journal of Medicine. She writes frequently in professional journals on a wide range of topics, particularly medical ethics. She is a persistent critic of alternative medicine, and in this interview talked to FRONTLINE about her skepticism about the efficacy and safety of many alternative therapies.

Tom Delbanco is a primary care physician at Beth Israel Deaconess Hospital in Boston and a professor at Harvard Medical School. He is the former chief of Beth Israel's Division of General Medicine and Primary Care. Delbanco co-authored the seminal 1993 New England Journal of Medicine Article which showed that a surprising one in three Americans were using some form of alternative medicine, and few were telling their physicians about it. He remains concerned that many people continue to turn to unproven--and potentially unsafe--alternative treatments.

Associate Professor of Medicine David M. Eisenberg is the Director of the Division for Research and Education in Complementary and Integrative Medical Therapies and the Osher Institute at Harvard Medical School. Dr. Eisenberg has served as an advisor to the National Institutes of Health, the Food and Drug Administration and the Federation of State Medical Boards with regard to complementary and alternative medicine research, education and policy. He has authored numerous scientific articles involving complementary and integrative medical therapies, most notably the 1993 New England Journal of Medicine report on the landmark survey showing that one and three Americans were using some form of alternative medicine. In this interview Eisenberg discusses how this survey paved the way for the tentative acceptance of alternative medicine within the conventional medicine community, and his concerns that much more research is necessary, especially on dietary supplements, before we know which alternative healing methods are safe and effective.

An internationally recognized expert in clinical research and clinical trials, Straus was appointed the first director of the National Center for Complementary and Alternative Medicine (NCCAM) at the National Institutes of Health in October 1999. In this interview, he discusses the economic, ethical, and methodological challenges of designing and conducting research on alternative medicine. He also defends a highly criticized NCCAM study on the popular herbal anti-depressant, St. John's Wort.

Andrew Weil is a nationally recognized leader in the integration of conventional and alternative medicine. A graduate of Harvard Medical School, he is the founder of the Program in Integrative Medicine at the University of Arizona Health Sciences Center in Tucson. Weil is the author of eight books, including Spontaneous Healing (1995), 8 Weeks to Optimum Health (1997), and Eating Well for Optimum Health: The Essential Guide to Food, Diet, and Nutrition (2000).

James Whorton is a Professor of Medical History at the University of Washington School of Medicine in Seattle and the author of several books, including Nature Cures: The History of Alternative Medicine in America. He has studied and written extensively about the history of alternative medicine, chronicling the field's ebbs and flows since the 1700s. In this interview, Whorton describes some remarkable similarities between other periods where alternative medicine was very popular and today, and looks at some of the economic and social forces fueling the current boom.