The integration of Semantic Web and Web Services technologies promises to be one of the most promising new areas for development of Intelligent Web Applications. One challenging area where these technologies meet is in explicit definitions of meaning for the messages exchanged between Web Services - in other words, semantic definitions of the meanings of data/commands exchanged in the execution of a Web Services based application. While current approaches such as OWL-S tackle these elements in service groundings by mapping processes to function calls with specific arguments, Agent Communication Languages could provide a potentially richer alternative. The work presented here shows how this could be done by mapping the existing Agent Communication Language (FIPA-ACL, FIPA-SL and associated standards developed by the Foundation for Intelligent Physical Agents) into OWL based representations which may then be readily used in a Web Services environment.