Private sponsorship in the budget of French universities has always been far below what it represented in Anglo-Saxon or German ones. This article aims at reassessing its importance for the University of Paris at the beginning of the twentieth century, driven forward by some voluntarist chancellors such as Louis Liard. It also draws a collective portrait of the donors, private or legal entities, who gave their whole fortune or part of it for the advancement of science, with a special focus on their motivation that often mixed up religious inspiration, republican involvement, pursuit of a social status and quest for power. It also highlights the difficult negotiations between donors and donees about the way their donation isused: some donors only intend to leave a trace in the history of the University but others claim a right to influence the content of the research they sponsor. On the other hand, the university is faced with a dilemma due to the conflict that exists between its need to attract sponsorship and its duty to avoid any kind of interference of private interest in scientific work.