A number of practices, once considered unorthodox, are increasingly being used by Americans and assimilated into medical practice. While many complementary and alternative medicine practices have the potential to prevent and treat disease and to improve understanding of how healing works, few have been tested rigorously. The mandate of the National Center for Complementary and Alternative Medicine (CAM) is to identify promising practices and use rigorous scientific methods to evaluate their effectiveness. The lecture reviews reasons Americans turn to CAM practices and features some of the research into what does and does not work. Dr. Straus has broad basic and clinical research experience related to many diseases and is an internationally recognized expert in clinical research and clinical trials. He was appointed Director of the National Center for Complementary and Alternative Medicine at NIH in 1999.