This chapter examines the concept of human security. It does so in descriptive, analytical, and empirical terms, drawing on both the scholarly and policy-relevant literatures. The chapter describes the development of human security, with references to the academic literature where necessary. Accordingly, the emergence, contribution, and impact of the most important drivers of human security, especially in institutional terms, are examined. These include the 1994 UNDP Human Development Report (HDR), the Commission for Human Security, the International Commission on Intervention and State Sovereignty, the Millennium Development Goals, and the International Criminal Court. The chapter takes up a recurring question about the newness of human security by looking at its intellectual and institutional genealogy. The chapter provides a detailed overview of the most trenchant critiques of human security. These critiques are placed into the following categories—too broad to be useful; national interest and co-optation; reformist tool of global capitalism; and neo-colonialism.