 Much of the philosophical literature connected with quantum theory centers on the problem of whether we should construe the theory, or a suitable extension or revision of it, in realist terms, and, if so, how this should be done. Various approaches to what is called the “Measurement Problem” propose differing answers to these questions. There are, however, other questions of philosophical interest. These include the bearing of quantum nonlocality on our understanding of spacetime structure and causality, the question of the ontological character of quantum states, the implications of quantum mechanics for information theory, and the task of situating quantum theory with respect to other theories, both actual and hypothetical. In what follows, we will touch on each of these topics, with the main goal being to provide an entry into the relevant literature, including the Stanford Encyclopedia entries on these topics. Contemporary perspectives on many of the issues touched on in this entry can be found in The Routledge Companion to Philosophy of Physics (Knox and Wilson, eds., 2021); The Oxford Handbook of the History of Quantum Interpretations (Freire, et al. eds., 2022) contains essays on the history of discussions of these issues.