Using the principle of cellular impedance, the xCELLigence RTCA eSight simultaneously monitors virus-induced changes in cell number, cell size, cell-substrate attachment strength, and cell-cell adhesion (i.e. barrier function). eSight couples this real-time impedance data with live cell imaging (bright field + 3 fluorescence channels) to provide an exquisitely sensitive and information rich interrogation of cytopathic effects that span the entire viral life cycle. In contrast to the canonical plaque reduction neutralization test which requires multiple handling steps and numerous days to complete, here I will present a simple eSight assay that identifies virus-neutralizing antibodies in as little as 5 hours. Beyond antibody screening, I will discuss the details of assay design/optimization and the use of eSight to quantitatively evaluate antibody efficacy by EC50s. Finally, it will be shown that the information richness of this assay lends itself to mechanistic analyses, making it possible to differentiate between antibodies which neutralize the same virus but do so via different mechanisms of action.