There is as much diversity within the private security industry as there are differences between public and private security providers. Whereas comparisons of the two modes of delivery have kept criminologists and economists fairly busy over the years, internal variations have not attracted the same level of interest. In the current environment, binary classifications such as the public/private security dichotomy might be too generic to capture the broad spectrum of unique security arrangements being adopted by various organizations. The aim of this article is therefore to offer an alternative conceptual framework that can account for the broad range of mechanisms responsible for the diversity of private security arrangements observed in late modern societies. The term ‘security regime’ defines the convergence of internal forces and environmental constraints that determine the conditions under which security is produced and exchanged by an organization. The four key dimensions (focus, risks, utility and constraints) that characterize a specific security regime were identified from interviews conducted with more than 50 security managers. The security regime approach should expand our knowledge of the various causes that facilitate, empower or hinder public–private relationships.