Abstract. Human being has always been looking for security. In traditional societies, because of smaller society, the spatial security rate and the social interactions rate were higher. as a result, more sustainable societies had been developed. But when the societies started to be crowded and expanded more, spatial structure and spatial relations in traditional societies started to be demolished and consequently the rate of social interactions and spatial security started decreasing, when the discussions about social sustainability with goals such as decreasing the security for human in social spaces started to be developed. In this research, in order to determine the relationship between the environment and behavior, the spatial security as an environmental factor and the social interaction as a behavioral factor were used. The spatial security could be investigated in two aspects: physical security and spiritual security. This study was a qualitative study that aimed to understand the characteristics of safe spaces in a way that the social interaction rate goes up. In addition, it would example some instances of the social places in traditional Iranian architecture. The study insists on the spiritual aspect of the security and leads to spatial security in three factor of: identity, sanctum and physical structure of space with effects on increasing the social interactions.