Under the terms of “new local actors of public security,” a plethora of small jobs of local social control with precarious status en uncertain definition are formalized. Generally, those workers are added on police actors and their missions are defined negatively with those carried out by those professionals. However, under a constant experimentation exterior, this kind of setting takes an increasing place in Belgium, not only in the framework of the so-called delinquency prevention policies, but also in the exercise of a local police function in search of its limits. Through the scrutiny of the “prevention and security assistants,” this contribution aims to display the sliding towards these of that police function exercise modalities and to answer the question of the complementarities between old and new uniforms.