Following the attack at Columbine High School in April 1999, the Secret Service and the Department of Education initiated a study of thinking, planning and other pre-attack behaviours engaged in by attackers who carried out school shootings. That study, the Safe School Initiative, was pursued under a partnership between the Secret Service and the Department of Education. This book examines the Safe School Initiative, whose objective is to attempt to identify information that could be obtainable, or "knowable", prior to an attack. That information would then be analysed and evaluated to produce a factual, accurate knowledge based on targeted school attacks. This knowledge could be used to help communities across the country to formulate policies and strategies aimed at preventing school-based attacks.