This conclusion presents some closing thoughts on the key concepts discussed in the preceding chapters of this book. The book begins with an introduction that lays out its goals and outlines the debate about causes for the emergence of private security markets. It then presents an analytic framework that specifies different possible market types, and seeks to illuminate their causes and consequences. Discussions of competing explanations feel cursory, and the analytic framework focused on market type does not address different levels of lethality or the distinction between domestic and external reliance on private security contractors satisfactorily. These matter to understanding the provision of security as a public good. Overall, though, both the analytic framework and the case studies contribute to the understanding of the ways in which private security is managed, and the effects that different kinds of private actors have on states and citizens.