What is the relation between understanding and knowledge in science? Can we understand a scientific theory if it is false? Do we understand a scientific proposition we can’t elaborate or do anything with? In Understanding, Explanation, and Scientific Knowledge (Cambridge University Press 2017), Kareem Khalifa argues for a revised version of a traditional view whereby understanding is a function of knowledge of an explanation. In his updated version, understanding admits of degrees, starting from minimal understanding. We improve our understanding by grasping more features in an explanatory nexus by considering plausible alternative explanations, comparing them and rejecting some, and committing to those that remain. Khalifa, who is professor of philosophy at Middlebury College, considers how his view compares with contemporary alternatives defended by Stephen Grimm, Duncan Pritchard, and others, including whether understanding requires some kind of special ability and what understanding adds in value to knowledge and explanation.