ABSTRACT Seven Central Yup’ik masks from Alaska owned by the Anima Mundi Museum, the ethnological museum at the Vatican, were examined in the museum’s Conservation Laboratory over five months in 2022 by Ellen Pearlstein, in consultation with Chuna McIntyre, a Yup’ik artist and culture bearer. Technical details were documented and these together with cultural meanings were explored jointly by the two authors. The authors explored the history of Catholic missionary acquisition and technologies available to Yup’ik carvers in the 1920s, and ways in which the masks departed from traditional technologies at the time of their manufacture and were altered since then within a museum setting. Such modifications were likely designed to permit Yup’ik masks to take on different functions than sacred or social performance, such that their authenticity might be questioned. In working as co-authors, the criteria for authenticity were defined to be whether the material manifestations of these Yup’ik masks evoked the intangible meanings understood by and significant to a Yup’ik culture bearer. The masks achieve this goal, as do contemporary Yup’ik masks that introduce additional new materials and techniques. It is impossible for non-Yup’ik to decide whether masks evoke sacred and social performativity, therefore conservators of other backgrounds are advised to collaborate with community members in their assessment of culturally distant materials.