This study aimed to investigate the factors affecting intention of citizens toward participating in activities related to development and protection of green spaces in Tehran. The research was descriptive-correlation and survey method was used. The statistical population of this study consisted of all citizens in Tehran. Using proportional and stratified random sampling, 626 citizens were selected as research sample. Questionnaire was used to collect data. The validity of the questionnaire was confirmed by a panel of experts from Tehran Municipality and faculty members of agricultural extension and education in Tarbiat Modares University. A pilot test was conducted to determine the reliability of the questionnaire. Cronbach's alpha was estimated between 0.87-0.91. The collected data was analyzed using SPSS software. Based on the research results, the intention for participation in protection and development of green space activities of 54.1 percent of the citizens were at a high level. There were significant differences between the different regions regarding the participation of the citizens. In this regard, the citizens of semi-marginal areas have more intention toward participating in green space protection. There were positive and significant relationship between number of received seedlings, number of reference for getting seedlings in recent years, citizens' perception of green functions, awareness of the destructive factors of green space, attitude towards investment in developing green and education of citizens, and protection and development of green space. Stepwise regression analysis showed that four variables included attitude towards investment in development and conservation of green space, citizens' perception of green functions, number of received seedlings and education are effective on intention toward participation.