This paper proposes an approach to behaviour-based discovery of Web Services by which business rules that govern service behaviour are described as a policy. The policy is represented in the form of ontological information and is based on actions relating to the service and conditions for performing them. The standard WS-Policy is used to associate such a policy to the Web Service. With a framework that extends standard discovery by UDDI, service consumers can query for Web Services by specifying business constraints. The policy of the Web Service will be evaluated against the consumer’s query by using OWL ontology querying engine and a rule-based reasoning module. By considering business rules in addition to the conventional attribute-based search by UDDI, the approach will enable more satisfactory discovery results that better fit service consumers’ requirements.