In recent years, the WSDL and UDDI standards arose as ad-hoc standards for the definition of service interfaces and serviceregistries. However, even together these standards do not provide enough basis for a service consumer to get a full understandingof the behavior of a service. In practice this often leads to a serious mismatch between the provider's intent and the consumer'sexpectations concerning the functionality of the corresponding service. Though additional standards have been proposed, a holisticview of what aspects of a service need to be specified is still lacking. This paper proposes a service specification framework, whichis based on a founded theory, the PSI-theory. The PSI-theory originates from the scientific fields of Language Philosophy and SystemicOntology. According to this theory, the operation of organizations is all about communication between and production by social actors.Based on the PSI-theory, a definition of the notion of ‘service' is given and a specification framework is derived. This framework canbe applied both for specifying human services, i.e. services executed by human beings, and IT services, i.e. services executed by ITsystems.