Corporate security units have emerged in municipal governments across North America. They resemble corporate security units found in private corporations, yet they are publically funded. Presently little is known about how the work of municipal corporate security units differs from that of public police, private contract security, or corporate security in the private sector. Though previous research has examined attitudes of public police toward private contract security, and vice versa, corporate security attitudes have been overlooked, as has how public sector corporate security personnel compare themselves to their counterparts in private corporations. This article extends analyses of ‘legitimation work’ of security and policing agents by examining what MCS personnel claim about public police, private corporate security, and private contract security. We show that MCS personnel claim the public police officers have a different skill set and possess limitations that MCS units overcome; that private corporate security is said to be driven more by a profit motive and is less accountable; and that private contract security agents have less expertise and are of lesser value than MCS personnel. Finally, we explore implications of this study for future research in policing and security.