During the 1991 excavation campaign of the University of South Florida, directed by Prof. J. Strange, in the National Park of Zippori in Israel, archeologists brought to light the main room of a public Roman building. The floor of the 100 square meter room is a polychrome mosaic dating from the III century A.D. As soon as it was excavated, the mosaic was protected by a temporary covering until the conservation intervention could begin. During the summer of 1995, the CCA, Centro di Conservazione Archeologica, carried out an in situ intervention using conservation techniques that respect both the materials and the technique of the original execution of the mosaic. Synthetic lifting materials were not used. This article will describe the methods and techniques that were used during the intervention. Special emphasis is given to those aspects that are peculiar to in situ conservation, in terms of planning and investment of human and economic resources.