This document describes investigations required for in situ preservation and monitoring of archaeological sites. It sets out the main parameters used to assess the state of preservation of archaeological materials and evaluate the preservation conditions of archaeological deposits and provides a framework for monitoring sites. A decision making framework is included to help readers make appropriate knowledge-based choices. The procedures described are appropriate for both terrestrial and underwater archaeological sites. The informative annexes relate primarily to terrestrial sites; for detailed technical guidance on investigating and monitoring marine sites, see sasmap.eu [6, 7]. NOTE Marine sites include all underwater sites and those in the intertidal zone.