The purpose of this primer is to provide the design community and school administrators with the basic principles and techniques to make a school that is safe from terrorist attacks and at the same time is functional, aesthetically pleasing, and meets the needs of the students, staff, administration, and general public. Protecting a school building and grounds from physical attack is a significant challenge because the ability to design, construct, renovate, operate, and maintain the facility is spread across numerous building users, infrastructure systems, and many building design codes. There is a strong interest in the United States (U.S.) in ensuring the safety of students, faculty, and staff in our schools. Schools are integral parts of their communities. Many schools are used as shelters, command centers, or meeting places in times of crisis. Schools are also used widely for polling and voting functions. In some communities, schools are places of health care delivery. Schools may or may not be the targets of terrorism, but they are certain to be affected by terrorism, whether directly or indirectly. On September 11, 2001, four elementary schools and three high schools located within 6 blocks of the World Trade Center were just beginning classes when the first plane hit the north tower. Thousands of children were exposed to the dust clouds from the collapsing buildings. Even those children not in the immediate vicinity experienced a great deal of anxiety. Children in at least three states (New York, New Jersey, and Connecticut) had parents working in or around the World Trade Center that day. In the Washington, DC, area, schools faced similar situations after the Pentagon was attacked. Many Americans feel that schools should be the safest place our children can be, perhaps at times even safer than the homes in which they live. Security is not a standalone capability; it is a critical design consideration that should be constantly reviewed and scrutinized from the design phase through construction or rehabilitation and onto building use. The focus of this primer will be on the threats posed by potential physical attacks on a school by terrorists. Attacking schools and school children could be a highly emotional and high profile event. At the time of publication of this primer, there have been no direct terrorist threats against a school known to the public; however, schools could be indirectly threatened by collateral damage from a terrorist attack directed at nearby facilities. Protecting a school against terrorist attack is a challenging task. A school may have considerable vulnerabilities, because of its well defined periods of use, designated access points, storage of sensitive personal information, minimal security forces, and numerous avenues of penetration and escape for attackers. This primer should be used in conjunction with the Federal Emergency Management Agency (FEMA) 426, Reference Manual to Mitigate Potential Terrorist Attacks Against Buildings, and FEMA 427, Primer for Design of Commercial Buildings to Mitigate Terrorist Attacks. This primer presents an approach to protecting schools at risk from terrorist attacks. The information presented is intended primarily for architects and engineers, or school administrators with a technical background. This publication is designed to meet the needs of all schools, including those with serious security concerns. Because security concerns of individual schools vary greatly, some users with modest security concerns may feel beleaguered by the amount of information and technical approach presented. They should feel free to select the methods and measures that best meet their individual situations while gaining a general appreciation of security concerns and risk management.