The present focus of this research has been on understanding the underlying processes involved in volume breakdown and surface flashover at atmospheric pressures. These events are studied under DC, pulsed, and HPM excitation. In the case of HPM induced surface flashover the breakdown threshold is characterized by observing Eeff/p vs. p*τ values experimentally and then using that data to improve the theoretical breakdown models. These models include Monte-Carlo type electron motion simulation codes developed in-house. A wide range of experimental variables are manipulated to gain further information on the breakdown formation such as gas type, gas pressure, field strength, surface features, pre-ionization sources, and superimposed DC fields. Recent efforts have also focused on measuring VUV emissions as only radiation below 180 nm (VUV) is energetic enough to cause photoionization, a critical process in streamer propagation during the initial phase of electrical breakdown. Currently very little is known about the VUV emission from gases such as nitrogen and oxygen at atmospheric pressures. These processes must be quantified to move existing breakdown physics models to a truly predictive level.