The Transportation Security Administration (TSA) has implemented a multilayered system composed of people, processes, and technology to protect the nations transportation systems. One of TSAs security layers is comprised of nearly 800 deployed explosives detection canine teams -- a canine paired with a handler. These teams include passenger screening canine (PSC) teams trained to detect explosives on passengers and conventional canines trained to detect explosives in objects, such as cargo. In January 2013, the United States Government Accountability Office (GAO) issued a report on TSAs explosives detection canine program. This book examines data TSA has on its canine program, what these data show, and to what extent TSA analysed these data to identify program trends; and the extent to which TSA deployed PSC teams using a risk-based approach and determined their effectiveness prior to deployment.