Fear of crime has become one of the most serious problems of our time, either as a result of living in neighborhoods objectively more 'dangerous', or of the diffuse fear and the obsession with security that characterizes today's society. According to a semiannual public survey, fear of crime and unemployment are on the top of main worries of Barcelona’s citizens. Together with the kind of social processes that characterizes public space in big cities (increased monitoring systems, privatization, standardization and avoidance) more complex patterns of uses and forms of occupation can be found because of higher rates of unemployment, poverty, ethnic diversity, new actors and forms of leisure. University of Barcelona and Barcelona City Council is carrying out a research on the relationship between fear of crime and public space's occupancy patterns. Our interest stems from 1) the risk that urban parks become more conflicted and marginalised areas, feared and avoided by certain groups and 2) the need of psychosocial and environmental evaluation strategies of public space to benefit planners, designers and policy makers.We have developed an ad hoc observation tool, EXOdES, which combines field formats and category systems to allow a systematic recording of variables of different nature (e.g., types of users, activities, psychosocial and environmental variables). During the last quarter of 2010, uses and forms of appropriation of 40 urban parks and squares in Barcelona have been studied. More than 35,000 series of data (or configurations) providing co-occurrence information about who is where, when, doing what, and in which environmental conditions, have been collected.A preliminary analysis of data to explore differences in types of users of public parks, activities and psychosocial and environmental variables regarding the level of perceived security in the neighborhood have been conducted. We have compared observed frequencies in 3 public parks located in high security perceived areas (Les Corts, Sarrià-Sant Gervasi and Gràcia) and 3 parks located in the lowest security perceived district (Ciutat Vella), according to the last Barcelona's Victimization Survey. The results in a sequential analysis suggest a significant lower presence of women and elderly, adults with children and adults with elders in public parks located in Ciutat Vella rather than in those located in high neighborhoods perceived security. Other differences include a significant presence of immigration, homeless people and signs of social and environmental disorder in low neighborhood perceived security.