Environmental non-governmental organizations (ENGOs) have emerged as important actors with regard to their interest in encouraging and supporting the dissemination of environmental policies. A key starting point in the examination of ENGOs and their influence on environmental policy is to highlight their decisions to affect policy processes as a means of achieving environmental protection. Hence, ENGOs need resources and it is equally important that they effectively employ those resources to achieve environmental policy influence. ENGO lobbying is a process in which different causal conditions interact with one another to affect environmental policy. However, minimal attention has been paid to how different conditions occurring together exert influence. This paper argues that it is the combined effect of resources and effective strategies that enables ENGOs to exert policy influence. Fuzzy-set qualitative comparative analysis is used to test the combined nature of different conditions. A dataset created in 2019 that includes 38 ENGOs from Turkey reveals that the combination of multiple interchangeable conditions leads to high ENGO policy influence. The findings suggest that advocacy effectiveness is achieved via two different causal paths. The first path entails having a large staff size, lobbying multiple venues, and using both inside and outside lobbying tactics, while the second involves large membership size, the use of both inside and outside lobbying, and lobbying multiple venues. This study suggests an alternative way of using the determinants of environmental policy influence and offers a new perspective for ENGO leaders to influence environmental policy.