The objectives of this study were: a) to measure the satisfaction of who volunteered in the activity, and b) to identify factors related to their satisfaction from the activities, and c) to provide policy implications to improve their satisfaction. This study was based on a literature review and empirical analyses. The empirical analyses have been completed through individual interviews with community residents who volunteer the NGO activities in the Korean Federation for Environmental Movement. The major findings from empirical analysis were as follows: As a result of correlation analysis, nine variables affecting the degree of their satisfaction were "activity time", "sex", "support of family and friends", "understanding of environmental NGO activities and fields of environmental NGO activities", "contact points for the activities", "income and vocation". As a result of multiple regression analysis, the five variables affecting the degree of their satisfaction were "understanding of the NGO activities", "income", "support of family", "marital status", "activity period" and these five variables explained 49.1% of the degree of their satisfaction. Based on the empirical findings, the following suggestions could be offered for the environmental NGO activities. 1) Environmental NGOs should offer resident-friendly programs which may help the residents participate in the NGO activities, so the volunteers can participate in the activities with their family, friends, and neighbors. 2) Environmental NGOs should provide appropriate information and educational supports to community residents, which might facilitate them to have a sound understanding of the NGO activities. And the environmental NGOs should provide diverse activity programs to facilitate participation and to formulate eligible management system for the activities. 3) To enhance the satisfaction of participation, environmental action programs should be organized and conducted through a careful consideration of the status of the community, the characteristics of residents, and so on. To provide better contact points, environmental NGOs should cooperate with religious organizations in communities, social groups, media and so on.