The paper sketches an account of explanatory practice in which explanations are viewed as answers to explanation-requiring questions. To avoid difficulties in previous proposals, the paper uses the structuralist account of theory structure, arguing that theories are complex and evolving entities formed around a conceptual core and a set of intended applications. The argument is that this view does better justice to theories which involve a number of different kinds of theory-elements to give narrative explanations. Theories are, among other things, (...) devices which can be used to turn explanation-requiring questions into a form which allows assessment of potential answers. Evolutionary theory, both in Darwin's and the modern synthetic forms, are used as examples. The view advanced is that modern evolutionary theory need not have a unique core to which other theories serve as subcontractors. (shrink)