Some 600 pipe bomb explosions per year have occurred in the United States during the past several years. How can we help protect the public from these homemade devices?This book, a response to a Congressional mandate, focuses on ways to improve public safety by preventing bombings involving smokeless or black powders and apprehending the makers of the explosive devices. It examines technologies used for detection of explosive devices before they explode -- including the possible addition of marking agents to the powders -- and technologies used in criminal investigations for identification of these powders -- including the possible addition of taggants to the powders -- in the context of current technical capabilities.The book offers general conclusions and recommendations about the detection of devices containing smokeless and black powders and the feasibility of identifying makers of the devices from recovered powder or residue. It also makes specific recommendations about marking and tagging technologies. This volume follows the work reported in Containing the Threat from Illegal Bombings (NRC 1998), which studied similar issues for bombings that utilize high explosives.