Explanatory reasoning is ubiquitous. Not only are rigorous inferences to the best explanation used pervasively in the sciences, this kind of reasoning is common in everyday life. Despite its widespread use, inference to the best explanation is still in need of precise formulation, and it remains controversial. On the one hand, supporters of explanationism take inference to the best explanation to be a justifying form of inference; some even take all justification to be a matter of explanatory reasoning. On the other hand, critics object that inference to the best explanation is not a fundamental form of inference, and some argue that we should be skeptical of inference to the best explanation in general. This volume brings together twenty philosophers to explore various aspects of inference to the best explanation and the debates surrounding it. These specially commissioned essays constitute the cutting edge of research on the role explanatory considerations play in epistemology and philosophy of science.