Ad hoc networks are inherently dynamic, with nodes entering, moving around, and leaving the network, often for short duration membership. This property of dynamic restructuring limits functionality and greatly complicates security. Here, we establish a foundation for analyzing ad hoc network functionality or security properties relative to their dynamic nature. The essential structure in any network is the links between nodes. Thus, our approach turns on measures of link availability to define network properties that govern functionality. In this chapter, we systematically address issues associated with changes that occur in ad hoc networks. We consider the functionality impact of change and address bounds on optimization that exist when change rates are high and provide definitions that allow reasoning about limits on functionality resulting from increasingly dynamic link activity.