Aside from classified publications, this technical monograph is likely the only text that addresses the topic of “Basic Intelligence.” The absence of scholarly treatments on Basic Intelligence indicates that the subject has been overlooked in the intelligence studies literature. Thus, this monograph breaks new ground by providing a concise discussion of the topic. The word “basic” describes something fundamental or something that serves as a foundation for further development or establishes the underlying basis for what could later be improved. When it comes to Basic Intelligence, one might naturally assume that this category of intelligence is rudimentary. However, it is not. Basic Intelligence is a distinct type of intelligence that requires planning and consideration similar to the other categories of intelligence—strategic, operational, and tactical. Basic Intelligence is utilized in background briefings, evaluations, assessments, estimates, and counterintelligence investigations. In this fifth instalment of the "Espionage Black Books" series, Dr. Henry Prunckun examines what Basic Intelligence is, how it fits into the broader framework of intelligence practice, the policies and procedures involved in collecting and archiving Basic Intelligence, and the standards used to assess the reliability and validity of these data.