This chapter gives a brief overview of The Sensitivity Principle in Epistemology, which presents state-of-the-art thinking about a very simple and intuitively compelling idea in epistemology. The book sparks renewed interest in sensitivity, perhaps restoring it to the throne of principles in externalist epistemology. Given the resilience of sensitivity, those who wish to reject sensitivity theories will try to uncover criticisms in addition to the several counterexamples that have been proposed and to the allegation that sensitivity forces us to deny closure. In this book, three prominent epistemologists, Jonathan L. Kvanvig, Jonathan Vogel, and Peter Klein, offer novel criticisms of sensitivity theories or steer extant criticisms in new and different directions. The book comprises essays defending the relative merits of safety over sensitivity. The book also includes a critical commentary by Anthony Brueckner on Sherrilyn Roush's (2005) Tracking Truth: Knowledge, Evidence, and Science.