The purpose and plan of the Handbook is described herein. Key concepts in the contemporary literature on reasons and normativity are introduced, and the forty-four chapters that make up the main body of the Handbook are each summarized. In the process, important connections between the chapters are highlighted. A distinctive feature of the Handbook is said to be the way in which it surveys work on normative reasons in both ethics and epistemology, focusing, when appropriate, on issues concerning unity or lack of it in different domains. It is noted that discussions of reasons and normativity in philosophy of language, philosophy of mind, and aesthetics are also surveyed in the Handbook.