Since crime is committed in a particular space, place-related factors can play roles in creating the potential crimes to be committed. Therefore, the issue of environmental prevention through planning and environmental design can lead to decrease of crime and offence problems in URBAN places. While, individual criminals found less opportunity to do offensive behavior in places that are planned and design by this purpose, it is possible to prevent criminal act in URBAN places and spaces by reducing the encouraging conditions to commit crimes in URBAN spaces. The relationship between environ- mental and site-specific characteristics of the affected locations were considered so that the role of these characteristics in crime can be determined in the formulation of prevention programs and the creation of safe URBAN spaces. In tum, these achievements can be applied in compiling codes of URBAN planning and design. The approach of the study was based on the scientific research method- ology of R. Quivy and LV. Comenhoudt introduced in their book "Manual de Recherché en Science Socials". Hypotheses and indicators were com- piled from observations and comparat1ve analyses of those URBAN spaces that are most often the sites of crime. The data provided the basis for strategic recommendations regarding URBAN planning and environmental design aimed at preventing crime. The theoretical background of this issue can be traced to URBAN Ecology studies, which have pro vided a scientific framework for recognizing reciprocal relations between humans and their environment. In 1971, following publication of the article "Crime Prevention through Environmental Design" by C.R. Jeffery, an important turning point came about in studying social abnormalities and crimes. Prior to this article, the dominant viewpoint in criminology was the study of crime itself. However Jeffery's ideas led to the consideration of CPTED as a methodology that could be implemented by URBAN planners, designers, and architects. In this framework, suitable and objective design in human built environment would reduce the feeling of insecurity in places by removing opportunities for crime, and thus improving the quality of life of cityresi dents and visitors. This approach was furthered by other authors, such as Elizabeth Wood, S. Angel, Oscar Newman, Alice Coleman, J. Wilson, and D. Hillier. According to the findings of this study (in the twelve sampled space city of Tehran), the paradigms of environmental planning can be nominated as the "invisible hand" of URBAN planning and design that can play an important role in the provision of safety and in preventing crime and other forms of social degradation. The results of this study were lead to introduce and establish new regulations for URBAN planners in High Committee on Architecture and URBAN Planning (Ministry of Housing and URBAN Development). By the way, this article is a part of a research program in 2006 that was entitled as "Compiling Environmental Codes to Prevent Criminal Action in URBAN Spaces", carried out in conjunction with the Iranian Center for Architecture and URBAN Studies and Research, according to the recommendation of the High Council of Iranian Architecture and URBAN Planning.