This document discusses public-private partnerships (PPPs) for digitizing cultural heritage collections. It outlines the objectives of both public and private partners in such partnerships. Public partners seek funding for digitization projects and ways to enhance access and engage new audiences. Private partners pursue commercial objectives like accessing new markets or building their brand through association with public cultural institutions. The document examines different models of PPPs and principles for ensuring they are balanced and maximize public access. It presents a case study of a large PPP between the Austrian National Library and Google to digitize the library's historical book collection in the public domain.