Uncertainty quantification (UQ) is essential for providing informative computational predictions in many branches of science and engineering. It is an interdisciplinary field built on a broad range of mathematical and statistical foundational topics, and associated algorithmic and computational developments. UQ20 will bring together mathematicians, statisticians, scientists, and engineers with an interest in the theory, development and implementation of UQ methods. While many topics will be represented, major conference themes will include the mathematical and statistical foundations of UQ, connections between physics-informed and data-driven UQ approaches and applications of UQ in the biosciences and climate science. The goal of the meeting is to provide a forum for the fruitful exchange of ideas between diverse groups of technical experts from academia and industry, thereby enhancing communication and contributing to future advances in the field.