Environmental problems such as air and water pollution, urban garbage and climate changes in urban areas are the results of human behavior. Only change in human behavior can reduce these environmental problems. Thus studying attitude and behavior of people is a precondition to change this situation. So the main objective of this study was to find out individual and social factors affecting environmental behavior of urban citizens. To achieve this objective a conceptual framework derived out from review of literature to examine relationships among personal factors, attitude towards environment and environmental behavior. To examine this conceptual model, 1200 individuals of Tehran residents were randomly chosen and interviewed about their environmental behaviors, opinions, knowledge and sources of information on environment. The data were analyzed using correlation analysis, student's t test, analysis of variance (ANOVA) and path analysis by SPSS software. It is emerged from the present study that education and improving problem-based knowledge of Tehran residents can change their environmental attitude and increase their feeling of stress towards environment. These changes in turn improve their preparedness to act friendly with the environment, particularly with the help of environmental legislation. Results of the study showed that environmental behavior of people in urban areas directly and indirectly are under the influence of variables like age, gender, income, education, problem-based knowledge, environmental legislation, environmental attitude, feeling of stress and preparedness to act of the residents. All these together can influence and change people's behavior to preserve urban environment.