Since the 1980s, public policymakers and contracting agents in the United States have promoted the concept of public-private partnerships (PPPs). These are typically seen as partnerships between the public and business sectors, but research finds that nonprofit intermediary institutions, either created for the purpose or already in existence, are often what makes it possible for PPPs to function and realize their potential. Nonprofits of this kind provide a "third space" in which PPPs can be formed, implemented, and sustained; they may also serve as value guardians of the PPP process. This article describes the essential but little credited role of nonprofit organizations in PPPs in the city of Cleveland, Ohio. Seven case examples illustrate the often-overlooked role of nonprofits and increase our understanding of the character and distinctiveness of PPPs within American civil society. Public managers, policymakers, and others concerned about the performance and management of PPPs, and desiring to stimulate their formation, will be well served to recognize the processes and players that nurture and bring together public sector and private business actors with nonprofits in the facilitation and institutionalization of PPPs.