This study reports the results of an empirical investigation into the ability of textbooks to form an effective ballistic shield that can be incorporated into school safety plans. The authors examine the history of assaultive violence with firearms in schools and the evolution of school emergency plans. The most common calibers used in school shootings were tested for their ability to penetrate hardback textbooks. The results indicate that most common handgun bullets can be stopped by only one or two textbooks and that even most assault rifle rounds can be stopped by three to five books. Examples are also provided on how law enforcement officers might incorporate the ballistic resistance of textbooks concept into a school emergency plan. (Published Abstract) Tables and references