International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper focuses on the development of the Surface-to-Air Missile Federation (SAM Fed), a Test and Evaluation (T&E) High Level Architecture (HLA) federation. The SAM Fed evolved from a legacy constructive real time/post mission hardware-in-the-loop (HITL) Surface-to-Air Missile (SAM) simulation. The process to transition from a standalone simulation to a distributed HLA federation as well as the problems experienced and lessons learned will be presented. This paper will also discuss the merit of standardizing internal federate interfaces to facilitate reuse.