Accurate measurements of trace gasses, such as nitrous oxide, methane, ammonia, and volatile organic compounds (VOCs), are increasingly important for a broad range of research and operation applications ranging from determining the transport and fate of agricultural emissions to predicting the impact of a changing climate. Nonetheless, collecting in-situ measurements of trace gas fluxes via eddy covariance, relaxed eddy accumulation, and other micrometeorological approaches remains challenging. This session will assess the state of the art of trace gas flux measurements by considering both recent advances in instrumentation and post-processing methods and their practical application in the field.