Abstract. This paper describes a sublanguage of Casl, called CaslDL, that corresponds to the Web Ontology Language (OWL) being used for the semantic web. OWL can thus benefit from Casl’s strong typing discipline and powerful structuring concepts. Vice versa, the automatic decision procedures available for OWL DL (or more precisely, the underlying description logic SHOIN(D)) become available for a sublanguage of Casl. This is achieved via translations between Casl-DL and SHOIN(D), formalized as so-called institution comorphisms.