This book is the result of what began more than a decade ago as a series of articles that were published in the Journal of the American Medical Association (JAMA). The series ran from 1993 to 2000. The forebears of this series were a similar but small series of articles published in the Canadian Medical Association Journal, beginning in 1981. But as well as a genealogy, this book has a pedigree. The father of evidence based medicine; David Sackett worked closely with at least some of the editors and contributors to this volume, and has clearly provided inspiration to the many fine contributors. His intellectual fingerprints are all over these pages – and a good thing too.