Ten years have passed since the last edition of this book. Much has happened in those years. Now thirty- nine states have right- to- carry laws, a huge increase from the eighteen states with them when David Mustard and I fi rst examined the relationship between such laws and crime. That original research in this book covered the sixteen years from 1977 through 1992. The second edition extended it by four years and covered twenty- eight states. Now, this new edition covers thirty-nine states and twenty- nine years from 1977 through 2005. That is a lot of crime data to study, especially with so many more states having adopted the law during the time. By now, dozens of academics have published studies on right- to- carry laws using national data. These studies have either confi rmed the benefi cial link between gun ownership and crime or at least not found any indication that ownership increases crime. Not too surprisingly, depending on the precise methods used and the exact data set, the results have varied. Some claim no effect from these laws, but not a single refereed study fi nds the opposite result, that right- to- carry laws have a bad effect on crime.