This article focuses on juvenile delinquency and on its perceptions in the last thirds of the 19th and of the 20th centuries. Three questions are discussed: Were there any debates on (human) security in both time phases and if yes, which problems were discussed; which larger social developments were mirrored in these debates; what were the implications of potential threats posed by juvenile delinquency for life in urban settings? In the last third of the nineteenth century the perception of and fears about youth crime focused on easily discernable proletarian male youth (groups and individuals) who mainly lived in densely populated urban neighborhoods. As (youth) crime was mainly interpreted as a threat towards the state and authorities were convinced that the police could successfully handle all challenges in this field, there were no debates about security at that time. In West Germany during the 1960s and the 1970s, two important changes in juvenile delinquency, in its perception and fears could be discerned. First, a twofold – spatial and social – dissolution of boundaries (Entgrenzung) of youth crime developed. The establishment of the transnational networks of the youth cultural underground, in which drug consumption played an important role, was instrumental in these developments. Second, in the early 1970s, as the case of the Rockers shows, youth crime had become a potentially omnipresent phenomenon of everyday urban life evoking diffuse spatial fears. Every seemingly friendly boy from the neighborhood could all of sudden turn into a “juvenile violent offender”. Thus, crime could potentially lurk everywhere, in every niche of (urban) society. It was against this background that the age of security dawned as it promised a safe haven against all future urban threats.