Active civil society is an essential part of modern democracy. An important part of active civil society are civil society organizations. Such organizations have emerged in many different fields, including the environment, which is the subject of this thesis. Environmental civil society organizations seek to pursue their interests like all such organizations in many different ways. One of the most important ways is influencing the formulation or change of public policies. The thesis deals with the impact of environmental civil society organizations on public policies in Slovenia during the current government period 2018–2019 and the reasons why the impact is as it is. Through an analysis of the literature, we identified three factors of influence of civil society organizations on public policies: the characteristics of organizations, whether there are competing organizations with conflicting goals in the policy network, and the attitude of state actors towards organizations. We tried to determine the impact and reasons for it through social interviews with the civil society and state actors. We found that it is impossible to determine the impact of environmental civil society organizations on public policies in Slovenia over the observed period unequivocally. Opinions on this differ between state and civil society actors. None of the identified factors of influence can be identified as the most important. It seems that which one is the most important differs from case to case.