For the past several decades, conventional flow cytometryFlow cytometry has been continuously improved for analyzing single cells and providing quantifying information such as surface protein copy numbers. However, using this tool, it is challenging to detect small extracellular vesicles (EVs) such as exosomes, which are ~30–150 nm in diameter, ~100-fold smaller in diameter, and one-million-fold smaller in mass than cells. Despite improvements in instrument sensitivity, flow cytometers continue to struggle to detect small EVs due to the limits of detection of sheath flow systems. Nevertheless, the number of publications related to EVs continues to increase exponentially because of the potential utility of EVs in drug delivery and disease diagnostics/liquid biopsy applications. New, high-sensitivity tools for phenotyping small EVs are urgently needed. Here we provide an overview of our efforts to overcome the obstacles to identifying and phenotyping small EVs.