School shootings have significantly impacted many aspects of our lives across the United States. They first became a recognized problem in American society in the 1960s and have since continued to increase in frequency and severity. Casualty numbers from school shootings have steadily increased since 1990, and even though such shootings are rarer than homicide, mass murder, and off-campus violence, they have a great impact on a community. Normally, techniques and tactics used by school administrations and law enforcement change over time to adapt to growing threats. Cases such as the University of Texas shooting in 1966 and Columbine High School in 1999, for example, led to changes in law enforcement tactics. While UT Austin and Columbine are landmark examples, from 2000 to 2015, there have been 45 school shootings. Attacks in Sandy Hook Elementary School and Marjory Stoneman Douglas High School have focused demands for change, and school and law enforcement procedures have not yet adapted to the rising threat. This book examines how educators, first responders, and law enforcement should respond to school shooters today using threat-assessment processes and facility security upgrades.