This introductory chapter to the Handbook frames the approach taken by the editors towards its compilation and discusses the various theoretical perspectives and the emerging norms and practices that comprise maritime security. It argues that maritime security has come of age, outgrowing its origins in national security. Embedded within the politics of everyday survival, maritime security remains a project of good order at sea. The sort of order and the means of attaining it have increasingly become open to contestation. The introduction visits individual chapters in the Handbook and contextualises the contribution each is making.