The military drawdown and budget cutbacks have created a greater emphasis on shorter, faster, and cheaper ways to do the mission. Modulation simulators have become a critical component in the evaluation and testing, and integration of new network, communications, and comrnand and control technologies and applications. This thesis evaluates five current commercial off the shelf products: OPNET Modeler by MIL 3 Inc.; COMNET 'I designed by CACI products Company ; Extend by Imagine That Inc.; Workbench created by Scientific Engineering Software Inc.; and G2 from the Gensym Corporation. Each of the products is evaluated using twenty-five primary evaluation criteria. The evaluations include current costs, completeness, user interface and post analysis support methods, and they describe the basic features and distinctive characteristics of each product. The capabilities of the products are compared, providing the reader with the knowledge to make an informed product selection based on the user's needs. A matrix of the products and the evaluation criteria provides a quick overview of the analysis.