The broad goal of this study was to gain an improved understanding for how synthetic jet actuators perform as flow control devices. This improved understanding is motivated by a need for enhancing and optimizing the design and operation of these devices for transition of the technology to larger scales. The term synthetic jet is generally used to describe the steady, turbulent flow that appears at some distance downstream of an orifice when an oscillating pressure gradient is applied across the orifice. Between the orifice, where the flow is purely oscillatory, and the point downstream, where an apparently steady jet exists, there exists one or more vortex rings. In the region of transition from an unsteady, periodic flow to a steady, turbulent flow, individual vortex rings are rapidly distorted by interactions with neighboring rings. The defining features of the vortex rings and how they interact with their neighbors are established during the time-periodic formation of the rings at the actuator orifice. These factors are also presumed to be closely linked to the defining characteristics of the ensuing steady, turbulent jet. Past work has shown quite convincingly that synthetic jets are tremendously useful for controlling flow at scales much larger than the synthetic jet itself (Amitay et al. 2001; Smith and Glezer 2002). However, despite numerous demonstrations of synthetic jets in flow control applications, the mechanisms by which a synthetic jet effects control are still not well understood.