In Stability and Reconstruction Operations (SRO), most recently typified by the Global War on Terror (GWOT) the US faces environments that require large and inexpensive forces that can operate effectively in protracted low-intensity environments. The US, however, has developed its land forces so that they are optimized for operational maneuver and deployment from strategic distances, and are therefore small, expensive, fast moving, firepower-intensive, and intended for short-duration engagements that seek to shatter similar enemy formations. The GWOT postulates successive campaigns for the foreseeable future; this requires the disengagement and reconstitution of forces between campaigns. If these campaigns are seen as large scale counterinsurgent "clear and hold" operations, then the counterinsurgent principle of holding cleared areas in order to prevent re-infiltration of enemy forces then becomes a concern. A third component, "build," is necessary to fill the vacuum left when US forces depart. Suitable local security institutions are the key to holding these areas, by sustaining security, allowing the disengagement of US forces for other efforts, and allowing stability to develop without substantial interference. Construction of such institutions is not without risk. Successful efforts can be built around the development of effective local security, however without culturally acceptable forms of such institutions there is a tendency for them to fail in the absence of their sponsor. Further, some security institutions create an undesired synergy with the negative elements of local cultures, especially in environments that lack the civil infrastructure to restrain them from taking political control. Designing institutions that are not merely culturally acceptable but that are also not culturally disposed to political opportunism and exploitation is a complex task that requires a deep and holistic understanding of the problem and the environment. This monograph examines this problem from a cultural standpoint, focused on internal security formations that are generally categorized as "constabularies." It does so by defining the environment and problem, examining the historic roles and elements of culture and constabularies, identifying elements common to successful constabularies, and listing cultural principles and elements for planning the establishment of constabularies. It then illustrates these constructs by examining two case studies, Haiti 1915-1934 and Morocco 1907-1919, that were selected for their specific cultural environments. It concludes by summarizing elements that allow constabularies to be successful, principles for the creation of constabularies, and the mitigation of the tendency toward Praetorianism. It concludes by discussing the political mechanism whereby the culturally successful creation and employment of a constabulary benefits sustained SRO such as the GWOT by allowing sustained operations over time at reduced direct political cost to the US or other such intervening powers.