This paper discusses the nature and the status of inference to the best explanation (IBE). We (1) outline the foundational role given IBE by its defenders and the arguments of critics who deny it any place at all; (2) argue that, on the two main conceptions of explanation, IBE cannot be a foundational inference rule; (3) sketch an account of IBE that makes it contextual and dependent on substantive empirical assumptions, much as simplicity seems to be; (4) show how that account avoids the critics' complaints and leaves IBE an important role; and (5) sketch how our account can clarify debates over IBE in arguments for scientific realism.