Natural resource decision making is changing. Previously, federal agencies made decisions about public lands and resources with one-way input from user groups and the public, but now agencies are collaborating more with stakeholders and the public to develop alternatives and choose a course of action. Changes in decision-making venues and procedures can have an impact on the representation of different interest groups, as some groups are better suited to take advantage of new opportunities than others. It is important to understand how the rise of collaborative decision making is affecting interest group representation, as it can alter not only interest group survival and influence, but also policy and management outcomes. This research examines environmental interest group participation in collaborative National Forest decision making to understand the differences between participants and non-participants in collaboration and to determine the extent to which there is equal representation of these groups under a model of collaborative governance. A survey was conducted on 101 environmental groups to test hypotheses about the dominantly theorized drivers of interest group behavior – resources and interest. Then, four organizations were chosen for case study analysis to examine the correlations in greater detail. The results indicate that resources are important for shaping the environmental groups’ ability to collaborate; organizations with larger budgets and a higher level of professionalization were associated with a collaborating strategy. Interest is important for shaping the environmental groups’ willingness to collaborate; organizations with multiple values were associated with a collaborating strategy, whereas organizations with a single, environmental value were associated with a confronting strategy. The results provide empirical evidence that smaller, less professionalized environmental groups and more ideological environmental groups are not well represented in collaboration. Given that collaboration is increasingly used to address environmental conflicts, the exclusion of these groups could affect their survival and influence on policy making, and could change the composition and influence of the environmental movement. Building organizational capacity, networking and encouraging alternative forms of participation in collaboration could help limit organizations’ marginalization under collaborative governance. Further, encouraging appropriate and legitimate collaboration, and upholding the legal foundation of environmental decision making will ensure that environmental organizations can participate in policy making through whatever strategy they choose.