In this research, the effect of the urban environmental stress on the subjective well-being of the people in a big city, also, a capital city such as Tehran has been studied. The objectives were to assess the perceived urban environmental stressors and to explore the coping strategies adopted by the people to combat the outcomes of Urban Environmental Stress. Perceived Urban Environmental stressors’ Scale (UES) and Urban Hassle Index were administered. The findings indicated that though people described their city as pleasant, a high level of stress was still perceived and its major reasons were found to be noise, waste accumulation, polluted air with smoke, and unhealthy environment in slums. The outcome of research suggests that the city planners should give equal priority to the natural resources and environment by various pollution management interventions and proper city planning. It is crucial for the well- being of the human beings to lower down the effect of stressors, so that the life in the city can be livable and of good quality. This paper provided guidelines for other metropolitan cities too for developing Environmental Competence and for generating mass awareness about the Urban Environmental Stress and its possible management options to help people develop Environmental Resilience and functional coping.