AFTER A GENERAL DESCRIPTION OF ELECTRONIC INTRUSION ALARMS, THE DOCUMENT DISCUSSES THE PRINCIPLES OF INTRUSION-DETECTION DEVICES OF THE FOLLOWING NATUREELECTROMECHANICAL, PHOTOELECTRIC, ULTRASONIC, MICROWAVE, PROXIMITY DETECTORS, AND AUDIO AND VISUAL MONITORING. THE DETECTION OF HIDDEN OBJECTS SUCH AS GUNS, KNIVES, AND STOLEN PROPERTY IS COVERED ALONG WITH DIFFERENT ALARM AND SIGNALING DEVICES THAT CAN BE USED IN CONJUNCTION WITH ANY OF THE DETECTORS DESCRIBED ELSEWHERE IN THE BOOK. ACCESSORIES SUCH AS POWER SUPPLIES AND ACCESS SWITCHES THAT ARE COMMON TO ALL SYSTEMS ARE CONSIDERED. EXAMPLES OF PRACTICAL INSTALLATIONS ARE GIVEN AND BUGGING, DE-BUGGING, AND SPEECH-SCRAMBLING SYSTEMS ARE EXPLAINED. THE FUTURE OF SECURITY ELECTRONICS, INCLUDING THE USE OF INTEGRATED CIRCUITS, IS DISCUSSED. (AUTHOR ABSTRACT MODIFIED)