The Irma synthetic signature model was one of the first high resolution Infrared (IR) target and background signature models to be developed for tactical weapons application. Originally developed in 1980 by the Munitions Directorate of the Air Force Research Laboratory (AFRL/MN), the Irma model was used exclusively to generate IR scenes for smart weapons research and development. In 1988, a number of significant upgrades to Irma were initiated including the addition of a laser channel. This two channel version was released to the user community in 1990. In 1992, an improved scene generator was incorporated into the Irma model which supported correlated frame-to-frame imagery. A passive IR/millimeter wave (MMW) code was completed in 1994. This served as the cornerstone for the development of the co-registered active/passive IR/MMW model, Irma 4.0. The latest version of Irma, 4.1, was released in April 1998 during the Aerosense Conference. It incorporated a number of upgrades to both the physical models and software. Current development efforts are focused on the inclusion of circular polarization, hybrid ladar signature blending, an RF air-to-air channel, reconfigurable sensor model, and enhance user interface. These capabilities will be integrated into the next release, Irma 5.0, scheduled for completion in FY00. The purpose of this paper is to demonstrate the progress of the Irma 5.0 development effort. Irma is being developed to facilitate multi-sensor research and development. It is currently being used to support a number of civilian and military applications. The Irma user base includes over 130 agencies within the Air Force, Army, Navy, DARPA, NASA, Department of Transportation, academia, and industry.