The paper discusses the version of entity realism presented by Ian Hacking in his book, Representing and Intervening. Hacking holds that an ontological form of scientific realism, entity realism, may be defended on the basis of experimental practices which involve the manipulation of unobservable entities. There is much to be said in favour of the entity realist position that Hacking defends, especially the pragmatist orientation of his approach to realism. But there are problems with the position. The paper explores two issues that reflect negatively on Hacking’s version of the entity realist position. The first issue relates to the role of description in fixing the reference of theoretical terms. The second issue relates to Hacking’s claim that the argument for entity realism based on experiment is a different kind of argument from the standard argument for scientific realism based on the success of science.