We propose an RDF-based language called SWCL to represent contracts, with a focus on service level agreements. The language came about due to a requirement in our research concerning reliable service delivery in domains containing virtual organizations, and we describe one such domain. Our language is built around a production rule system using RDF bindings and containing some contract-speci c resources. A number of other approaches to contracting have been proposed, and we rst describe these, and then compare them to SWCL. Finally, we suggest a number of extensions to this work, as well as ideas regarding how contracting can form part of a framework for increasing agent reliability in an open environment.