Much of the literature on multistakeholder partnerships that addresses grand challenges has extolled the virtues of such partnerships as a means of reducing uncertainty, acquiring resources, and solving local and global wicked problems. These virtues include opening up “access and agendas to wider participation” (Gray 1989: 120), coordinating across jurisdictional boundaries, mobilizing diverse and heterogeneous actors, and generating novel solutions to address these complex problems. Yet partnerships are not panaceas, and the reasons they fall short of their stated aspirations remain underexplored. We argue that attention to the political landscape, and particularly who has power and who does not, can account for the shortfalls of many partnerships. Theory and practice can improve by considering power dynamics in the institutional field that shapes the context in which partnerships emerge and unfold and influences the problems partnerships are designed to affect. We consider four field conditions that differ with respect to the degree of power and alignment of goals among actors in the field. We discuss four trajectories of change originating from each of these field conditions that describe shifts in field-level power or alignment of goals: collaboration, contention, consciousness raising, and compliance. We explore the dynamics associated with each trajectory to show how fields may shift toward or away from conditions conducive to building and sustaining collaborative partnerships around grand challenges.