The seventeenth and eighteenth centuries have long been recognized as an especially fruitful period in the history of Western philosophy. Most often this has been associated with the achievements of a handful of great thinkers: the so-called “rationalists” (Descartes, Spinoza, Leibniz) and “empiricists” (Locke, Berkeley, Hume), whose inquiries culminate in Kant’s “Critical philosophy.” These canonical figures have been celebrated for the depth and rigor of their treatments of perennial philosophical questions, concerning, for example, existence, modality, causality, knowledge, obligation, and sovereignty, as well as for their efforts to push philosophy in new directions, challenging many of the assumptions of ancient and medieval philosophy. In this connection, it has been argued that epistemology assumes a new significance in the early modern period as philosophers strive to define the conditions and limits of human knowledge. Yet early modern philosophers make major contributions in almost every area of philosophy, and in many cases their conclusions continue to serve as starting points for present-day debates. The chapters in this Companion are designed to acquaint the reader with the most important developments in early modern philosophy and to point the way toward more advanced studies in the field.