Unmanned Aerial Vehicles (UAVs) presently under consideration by the Program Executive Officer for Cruise Missile Projects and Unmanned Aerial Vehicles (PEOCNPUAV) will be equipped solely with electrooptical (EO) sensors. This thesis provides a comparative analysis of the mission effectiveness between UAVs equipped with EO sensors and those equipped with a multiple sensor system payload. A historical review of UAV development and employment is provided so that the reader may gain some insight into past UAV shortcomings in the hopes that they might be prevented in future systems. A typical Reconnaissance, Surveillance and Target Acquisition (RSTA) mission scenario is defined and a comparison made between UAVs equipped with EO sensors and those equipped with multiple sensor system payloads. he measure of effectiveness used for this comparison is the time required by the UAV to search 100 percent of an assigned area. The physical and operating characteristics of available sensor systems are discussed in detail. We develop an optimization model for selecting multiple sensor payloads from those sensor systems described. The model considers the sensor's physical characteristics, unit cost, identification capability and false alarm rate when determining the optimum payload. The optimum sensor system payloads are selected d the best alternatives to EO sensors for performing RSTA missions in a hostile environment are recommended under a range of budgets.