In this thesis I study the global phenomenon of environmentalism from the point of view of a local NGO. I base my study on long-term fieldwork done with an environmental organisation in Quito, Ecuador. My aim is a two-fold analysis. First I look at the relationship between radical environmental ideology practiced in a 'closed' group on the one hand and the members' sense of belonging and self-understanding on the other. Secondly, I look at the relationship between radical environmental ideology and the group's outwardly directed activities. I approach this by three main avenues. First, I focus on the group's version of radical environmental ideology and particularly its quality of being both all-encompassing and confined. Second, I look into the organisation of the group itself, in particular as it can be seen as an endavour to create a mini-version of the ideal society within the group. Finally, I examine the members' outwardly directed practices with which they seek to change the world. I show that ecologism and the way the members practice it, is first and foremost about social justice. The group aims at political and radical change, and ecologism is a language through which critique of the present society can be formulated. I argue that the members with their ecologist activities create new political fields and new political actors. This activity can pose a challenge to a hegemonic discourse focused on 'progress' and 'development' espoused by the State and capitalist elites. At the same time, while aiming to change the outside world, the members construct their own community within the group. They create their own world to which they can belong, and which, by participating in it, shapes their identities. Ecologism, I will argue, provides the members with alternative femininities, and the group is an arena for the experimentation, authoring and rehearsing of new worlds, and in turn, new selves.