Contemporary cities are increasingly characterised by ‘super diversity’. As Putnam’s thesis about the negative social consequences of ethnic diversity is correct, we may assume that growing diversity also negatively affects crime and fear of crime in cities. After all: the more diversity, the less social cohesion and the less collective efficacy, ultimately resulting in higher crime rates. More diversity also implies less (public) familiarity in neighbourhoods and more fear of crime. On the other hand, some qualitative studies show that particularly residents of relatively homogeneous districts perceive migrants as threatening. Migrants are seen as less threatening when neighbourhood residents are familiarized with ‘the other’ and when there are more interethnic contacts. Various foreign and Dutch studies show an independent effect of ethnic diversity in the neighbourhood on fear of crime. However, this effect disappears when other resident characteristics are included into the analysis. Residents of ethnically diverse and deprived districts are generally less satisfied with their neighbourhood, have less trust in the government and are more often victimized. Precisely these perceptions and experiences explain why they more often feel unsafe in their own neighbourhood.

How could positive security policies take shape? On what kind of empirical research should these policies be based? And what sort of concepts would we need for this development? If the starting point is to understand safety as a positive notion, it seems wise to avoid the terms of war that are prevailing in current policy programs on security and public safety (fighting, frontline and city-marines). On the other hand some type of decisive jargon might be unavoidable when one sets out to have an actual impact on youth crime policies and policy makers. Is it possible to keep using some type of military terminology in research benefitting the development of positive security policies and still emphasize a positive composition? This dilemma has arisen in recent research activities on positive, street-oriented role models in response to Dutch problematic youth groups and youth at risk. De Jong argues that with the sensitizing concept of the ‘liaison officer’ it might be possible to encourage a positive change through applied social science.