Some global trends (economic crisis, juvenile dispossession, unemployment, ethnic diversification, new types of social fractures, etc.) are exercising a direct impact on the complexity of uses and occupations of the public spaces and, therefore, on its governance (Brown, Perkins, & Brown, 2003). The fact that a major complexity of uses seems to be related to an increase of the conflict in the public spaces and of the perception of civil insecurity (Fernández, & Corraliza, 1996), is paying to a major interest for the development of technologies that allow to evaluate the environmental quality of these spaces and the uses that the citizenship does of them in an attempt of promoting public effective policies. This paper presents an instrument to evaluate uses and environmental characteristics of public spaces, as result of perfecting and fitting the technique for recording information based observational category systems and the implementation of Field Formats (Anguera y Blanco, 2003; Castellano, 2000; Gorospe, 1999; Ardá, 1998;Hernández- Mendo, 1996; Anguera, 1979) -a technique widely used in Sport Psychology (Gorospe et al, 2005; Castellano y Hernández-Mendo, 2000) but unprecedented in Environmental Psychology. Its creation is the result of an effort to provide systematizing and rigorous to the observation tasks of public spaces. The instrument EXOdES has been used for the evaluation of the uses of various public places in the Guinardó neighborhood in Barcelona. This research has been supported by the Barcelona’s City Council, and the Prevention Services Agency. Further analysis of the data with specific GSEQ software (Bakeman y Quera, 1996) has allowed a description of the types of actors that use the space, the activities it carried out and evaluation of certain environmental indicators as environmental features, or both social and physical incivilities (Lagrange, Ferraro & Supancic, 1992; . Psychosocial indicators referring to environmental quality, perceived satisfaction with the place, and fear of crime have also been introduced in the analysis (Robinson, Lawton, Taylor, & Perkins, 2003). Part of the results are compared with some of the existing literature regarding the characterization of the dangerous places and the fear of crime (Jackson y Stafford, 2009; Carro, Valera y Vidal, 2008; Amerio y Roccato, 2005; Pain, 2000). Finally, the emphasis is in the process of preparing the instrument for collecting observational data intended to be useful for the proliferation of new studies based on observational analysis of public space.