Non-Gaussian functional integrals arising in Quantum Field Theory are notoriously difficult to define and compute. This applies even to relatively simple models such as Chern–Simons gauge theory, where an exact solution was obtained without a direct evaluation of the functional integral. I will explain how to use supersymmetric localization to reduce in some cases a non-Gaussian functional integral to an ordinary integral. This technique can be used to evaluate ex-
actly some observables in Chern–Simons theory as well as in certain
supersymmetric gauge theories in three dimensions and to test various
duality conjectures concerning such theories.