The Colorado Basin Roundtable is a participatory policymaking process composed of representatives of water policy and management interests. This thesis argues that the public participation literature has excelled at understanding processes like these, by exploring how individuals should have opportunities to interact and make decisions within these processes. However, this body of theory has stopped short of understanding the role of interests and representation in a participatory process, due to its focus on "public," most broadly defined. Where public participation fails, policy literature can add in its understanding of interests and coalitions; yet, policy theorists are focused on the political context and thus largely ignore the importance of the design of the process. This thesis brings the two bodies of literature together to propose a new model for looking at participatory policymaking processes that includes interests and interest groups. A participatory process can include individuals appointed to the process who represent interests and whose interactions with each other are influenced by their interests, not just the design of the participatory process. To explore these concepts, the study of the Colorado Basin Roundtable collected survey information from 160 respondents, including 46 on the roundtable and outside stakeholders. Questions on beliefs were analyzed using k-means cluster analysis to create the belief coalitions, and the remaining data was used to better understand interactions within the beliefs coalitions and at the roundtable. Membership in belief clusters was found to have a significant relationship to reports of information sharing and trust with other members of the roundtable. However, membership in belief clusters was not found to have a relationship with key demographics often used to select members of a participatory policymaking process, such as age, gender, and organizational affiliation.