Numerous ethical issues were raised and cultural differences were heightened as American and Mexican conservators recently worked together on a joint international project to preserve and protect a major collection of rare and exceptionally fragile pre-Columbian mural fragments which had been donated to the Fine Arts Museum of San Francisco. This paper presents the following topics: brief descriptions of the collection needing treatment and the Bilateral Agreement signed between the Fine Arts Museums of San Francisco and Mexico's National Institute of Anthropology and History; meeting of the conservators concerning areas of disagreement and cultural differences in approach; the negotiation process; the reconciliation process; and, finally, the future of the fragments and the limits of object care.