Significant progress in fulfilling the current joint Air Force/Navy `Smart Metallic Structures (SMS)' program primary objective, to demonstrate a viable structural health monitoring system (SHMS) for a large structural aircraft component, is presented. Structural health monitoring and its relation to current Force Management (FM) and Aircraft Structural Integrity Program (ASIP) procedures are first reviewed together with a brief status overview of the relevant sensor technologies (e.g. AE, fiber-optic, corrosion, etc.). Key features of the SHMS architecture are described for the selected F/A-18 bulkhead and T-38 wing spar structural demonstration articles, highlighting sensors, processors, data busses, hardware, and software. Results from acoustic monitoring of the program sub-element structural tests are presented in some detail along with a status review of the SHMS multiplex bus component hardware and software. Finally, structural requirements for an SHMS meeting minimum ASIP guidelines for damage detection are discussed along with foals for future testing and development of the SHMS under the SMS program.