Although several internal and external factors may influence environmental non-governmental organizations’ (ENGOs) action sets and networking behaviors, their values and priorities deserve special attention. Existing research highlights the importance of mobilizing resources and utilizing political opportunities in environmental advocacy; however, there is relative silence regarding the impact of how ENGOs cognitively position themselves in a contested field. Through a quantitative analysis of survey data from 117 local ENGOs in the Aegean Region of Turkey, we examine whether and how organizational identity, scope of environmental issues, and core environmental purpose (transactional or informational) as three cognitive filters play a role in shaping grassroots ENGO activities and relationships with diverse actors. A set of regression models indicates that claiming an activist identity, pursuing a higher number of environmental issues, and having a confrontational goal significantly influences local ENGOs’ strategic actions and the type and intensity of their external ties. These findings contribute to the discussions around resource mobilization theory and the political opportunity structure framework by highlighting the importance of intangible, less visible, ideological dimensions, and of cognitive framing in mobilizing for environmental causes.