This paper explores how organizations innovate collaboratively with multiple partners. While research about multipartner alliances often treats them as a collection of independent dyads, this view neglects the possibility of third party influence and interference in dyads that can inhibit innovation in organizational groups. How organizations innovate with multiple partners in light of these problems is not clear. Using a multiple case, inductive study of six triadic groups of organizations engaged in technology and product development in the computer industry, this paper examines the collaborative forms and processes that organizations use to innovate with multiple partners in groups. Groups using two collaborative forms – parallel dyads and unified triads – generated mistrust and conflict that stemmed from interactions with third parties. These groups had low innovation performance and weaker ties in this study. Yet other groups were able to avoid these problems using unique supradyadic mechanisms – isolating third parties and linking dyads between different pairs – to generate a sequence of innovative collaborations that cycle through combinations of partners in the group and strengthen ties. The main theoretical contribution is to research about the organization of innovation by re-framing multipartner collaboration as group dynamics that shape innovation.