Aware of the prevalent and increasing use of complementary and alternative medical (CAM) therapies, we became convinced that discourse about the effectiveness and safety of commonly used CAM therapies would be of value to the Annals readership—hence, the series of papers on the topic that begins in this issue (1–2). This special series of invited papers consists of reports of original health services research, critical reviews of the literature, and commentary on a variety of CAM-related issues. It does not include original research that directly addresses the clinical effectiveness of specific CAM therapies, but that is not our purpose. Our intention is rather to provide physicians with synoptic reports of the state of the science for commonly used CAM therapies, thought pieces addressing the broader social aspects of CAM therapy (including credentialing of practitioners, legal and ethical concerns), and discussion of topics pertaining to CAM research (including placebos, medical pluralism, taxonomy, pharmacology of herbal products, and the rules of scientific evidence). Taken together, the articles in this series are intended both to provide useful information to practicing clinicians and to stimulate further research and policy development in this area. Publication of the series reflects Annals' continuing interest in the practice of medicine in the broadest sense. As always, we encourage readers to share their reactions and comments with us.