Capabilities of civil society organizations (CSOs) largely depend on two interrelated factors, the legitimacy of CSOs in the eyes of society at large and their interactions with the state as well as donors. Their legitimacy is in turn reflected by their membership base and the public support they can muster, which depending on CSOs'' organisational characteristics can increase or decrease. In this context, this paper is based on an extensive field research that investigates the relations of environmental CSOs in Turkey to donors and the state as well as their organizational structures. For the purposes of the research, the most important environmental CSOs in terms of size, areas of impact, visibility, national coverage, access to international networks and funding were selected and 45 in-depth interviews were conducted with CSO directors and employees, relevant state bureaucrats and parliamentarians, representatives of financial donors and sponsors, and international organizations (e.g. UNDP, REC Turkey, and EU Commission) and other experts. The cases selected are at the same time the organizations which have been most inclined to professionalization, raising the question of how this process of professionalization has impacted the extent of membership base and general public support. Based on this data, we construct an organizational mapping tool conceptualized on the following dimensions: the degree of institutionalization, politicization, financial autonomy, localization, specialization and involvement in policy making. Such a mapping enables us to evaluate the capabilities and limits of CSOs in terms of their contribution to democratization and participation as well as fulfilment of self-identified .goals, in this case effective environmental protection.