In this thoroughly updated and revised edition of Counterintelligence Theory and Practice, Hank Prunckun provides all of the elements required for a successful counterintelligence operation from both an academic and a practitioner's point of view. It offers an advanced understanding of the underlying theory that supports the art and science of the craft, and examines the challenges and practicalities of defensive and offensive counterintelligence. Designed for students in intelligence studies as well as professional training classes, this text explores issues related to national security, military, law enforcement, and corporate as well as private affairs.