This paper documents the design and testing of a prototype laser/radio frequency (RF) Soldier Identification (ID) System developed by Dynetics, Inc., Harris, Corp., and the U.S. Army Communications and Electronics Command (CECOM). The Soldier ID system consists of an Interrogation Unit, a Responder Unit, and a Programming Unit. The Interrogation Unit consists of a directive, eyesafe laser and a spread-spectrum RF transceiver. This allows for a low probability of intercept (LPI) interrogation, which is of interest during covert operations. A Responder Unit is worn, for example, by a soldier and transmits an LPI spread-spectrum RF response, only after receiving the proper interrogation codes. The operating principles for the subsystem are reviewed, and key design issues are presented. In addition, both breadboard and prototype test results are presented.