One day, in a moment of weakness, I fell prey to the temptation to organize and edit this volume on the mechanism of insulin action. The major reason for attempting to resist, of course, is the amazing speed at which advances are being made in this field. The usefulness of books such as this is often quickly compromised by new findings obtained during and just after publication. Happily for the contributors to this volume and myself, this unfortunate fate does not appear to be in store for us. New and important findings will undoubtedly continue to flow in this field during the next few years, but I believe this will increase rather than decrease the usefulness of this volume. As a matter of fact, as we go to press, I am delighted both that I was tempted and that I failed to resist. There are two basic reasons for my enthusiasm about this book, and they both relate to this issue of timeliness. First, each of the contributors has had an opportunity to update the scientific content of the various chapters only a few months before actual publication of this volume. The material presented in this volume is, at publication, contemporary with the current original literature. This volume thus provides an ex­ cellent framework for assessing new discoveries in this field for some time to come.