Collaborative processes are widely used to harness resources for addressing community problems. Despite their positive potential, collaborative projects can fragment. Sources of fragmentation include participant misperception of facts, difficulties in defining the problem, and misunderstandings among stakeholders. Disruptions from these elements may impede a group's progress in fostering and implementing agreements. Theoretical and empirical research from conflict resolution has shown that discussing participant interests and the use of facilitation techniques can help negotiators engage in innovative problem solving. Interests are participants' underlying needs, concerns, and desires that shape how individuals perceive issues and the stances they take. Less attention has been given to designing multi–party collaborative processes so that participant interests are explicitly defined and addressed. This comparative case study used mixed methods to examine the role of interests on the evolution of five successfully implemented multi-party collaborative cases. The research examined how participant interests were identified, how facilitation techniques were used, and how stakeholders' interests were addressed in each case. Results show that in all cases, identifying participant interests helped participants understand the central problems, seek information, and use creative problem solving. The use of techniques such as clarifying questions and shared learning experiences in the context of regular face-to–face meetings fostered participant understanding of the issues and each others' interests. In four of the five cases, participants' understanding of other stakeholders' interests affected their perspective on the issues, improved understanding of individual barriers, shaped the agreement, and motivated participants to stay committed to the project. Project staff members and participant leaders used facilitation techniques for identifying actors'’ substantive interests and clarifying issues. These techniques addressed participant relationship and process interests. In the cases with higher levels of fragmentation, participant interests were connected to values, individuals used competitive bargaining tactics, and trust influenced the willingness of participants to share interests. Facilitation techniques were crucial for encouraging trust building among stakeholders and for managing disruptions. These findings indicate that managers will increase problem solving capacity in collaborative processes by explicitly using negotiation-–based facilitation techniques to identify and address participant interests.