Based on a series of interventions in a number of institutional homes for underage youth and young people of age, the authors intend to show the main causes of insecurity of educational staff while working. For these professionals, insecurity at work mainly refers to the growing violence these young people demonstrate, and they wish to draw specific attention to the fact that the profile of these teenagers is constantly deteriorating. However, an in-depth analysis over a fifty-year period reports that institutional placing can call this hypothesis into question. Rather than taking into account the profile of the placed teenagers, the working conditions and the exercise of the profession should be analyzed. Their progressive security seems to be a counterpart to an increasing awareness of professionals as to the otherness of the teenagers, who appear to be less and less accessible.