Abstract. This paper presents a framework for monitoring the compliance of systems composed of webservices with requirements set for them at run-time. This framework assumes systems composed of webservices which are co-coordinated by a service composition process expressed in BPEL and uses event calculus to specify the requirements to be monitored. These requirements may include behavioural properties of a system which are automatically extracted from the specification of its composition process in BPEL and/or assumptions that system providers can specify in terms of events extracted from this specification. .