Numerous applications require aerial surveillance. Civilian applications include monitoring forest fires, oil fields, and pipelines and tracking wildlife. Applications to homeland security include border patrol and monitoring the perimeter of nuclear power plants. Military applications are numerous. The current approach to these applications is to use a single manned vehicle for surveillance. However, manned vehicles are typically large and expensive. In addition, hazardous environments and operator fatigue can potentially threaten the life of the pilot. Therefore, there is a critical need for automating aerial surveillance using unmanned air vehicles (UAVs). This paper gives an overview of a cooperative control strategy for aerial surveillance that has been successfully flight tested on small (48-in wingspan) UAVs. Our approach to cooperative control problems can be summarized in four steps: 1) the definition of a cooperation constraint and cooperation objective; 2) the definition of a coordination variable as the minimal amount of information needed to effect cooperation; 3) the design of a centralized cooperation strategy; and 4) the use of consensus schemes to transform the centralized strategy into a decentralized algorithm. The effectiveness of the solution will be shown using both high-fidelity simulation and actual flight tests