A description of the Logistics Composite Model (L-COM), a computer model developed to simulate the overall operations and support functions at an Air Force base. L-COM consists of three main programs: a preprocessor, a simulation program, and a postprocessor. The model replicates the flying of aircraft; accomplishment of servicing tasks; incurrence of malfunctions; flight-line maintenance; repair of components in base repair shops; the utilization and interaction of resources in the demand process; and the changes in resource availability according to shift policies. L-COM has two unique features: (1) a task network that describes base processes to be simulated by identifying particular tasks and the sequence for accomplishing them; and (2) embedded decision routines that help determine a best mix of resources to support a prescribed flying program. The model requires a computer with an internal memory of at least 65,000 words of 36-bit length or equivalent. A typical problem requires from 1-1/2 to 2 minutes of computer time to simulate a day's worth of base operations involving 1,500 tasks. Since L-COM is written in SIMSCRIPT, almost any computer of sufficient size may be used.