Almost twenty-five years ago, shortly after the arrival of triple therapy on the market, new forms of memory emerged in response to the human and cultural loss caused by the HIV/AIDS epidemic. Between 2002 and 2005, two anthropologists, on behalf of the Musée Ncational des Arts et Traditions Populaires (MNATP) in Paris, conducted an investigation and gathered objects connected to the history and memories of AIDS in France, Europe, and the Mediterranean, collecting over 12,000 artefacts (documentation, prevention equipment, objects used during demonstrations, etc.) from numerous associations as well as activists. As the gathering campaign ended, the Parisian museum closed down and its collections were transferred to the Musée des Civilisations de l’Europe et de la Méditerranée (Mucem), which was inaugurated in 2013. This article tells the story of the process of musealization of two dresses preserved in Mucem, which once belonged to the Sisters of Perpetual Indulgence, an activist movement committed to fighting HIV/AIDS. What does an activist object gain, and lose, when it is added to a museum collection? What became of the data that were coproduced in the field during the gathering initiative conducted by the anthropologists and their partners, which were meant to document the contexts in which the ethnographic objects were used? What happened when a Sister in the present applied to the museum to access the items of a Sister from the past, and what type of knowledge, documentation, or new objects could the former bring?