The annual CLEERS conference sponsored by the U.S. Department of Energy and organized by the Oak Ridge National Laboratory was held in Ann Arbor, MI, 18–20 September 2018. It brought together emission control scientists, engineers, and investigators from academia, national labs, and industry from across the U.S. and abroad, discussing the latest emission control technologies, trends, challenges, and regulations. Presentations, deliberations, exchanges, and panel discussions displayed a much-needed focus on the latest up-and-coming approaches to further advance NOx reduction, a major remaining challenge especially in diesel emission control, using further advances in selective catalytic reduction (SCR) of NOx, passive NOx adsorbers, lean NOx traps, and SCR on particulate filter, amongst others. Discussions were further held on diesel oxidation catalysts, gasoline particulate filters, three-way catalysts, and hydrocarbon SCR, and also on the latest catalyst washcoat technologies, materials, and catalytic processes such as diffusion and kinetics, testing, and computer simulations.