Public-private partnerships have become an important aspect of public administration theory and practice both in the United States and internationally. The National Archives and Records Administration, in partnership with private support foundations, administers 13 individual presidential libraries that make up the Presidential Library System. These privately constructed, publicly supported archives not only preserve official presidential records, but through their museum displays, also offer visitors a glimpse into the life and times of specific presidents. Although many consider these partnerships vital for the continued success of the Presidential Library System, relatively little is known about them. This qualitative case study explores the nature and extent of the public-private partnerships in the Presidential Library System, focusing on libraries established following the Presidential Records Act of 1978. Key themes related to the nature of these simultaneously mandated and voluntary relationships are their informal governance, decentralized administration, and increased reliance on private resources. This research has implications for both theory and practice of public-private partnerships in general as well as those supporting sites of collective memory such as archives, museums, monuments, and memorials.