The role of lichens in the deterioration of a wide range of archaeological materials is reviewed. Italian stone and art work in exposed and partially enclosed environments were examined in detail to identify those substrata most vulnerable to lichen attack. Relationships among particular species and the physical and chemical nature of their strata are being assessed in order to determine the relative importance of lichens in biodeterioration processes obtained in specific circumstances, and to establish precisely those species which are responsible for disfigurement and those that cause actual destruction. Specific reference is made to research currently being carried out on both in situ and relocated building materials, ornamental carvings, terracotta pots, and frescoes at numerous archaeological sites and open air museums in Italy.