This paper reports on work in progress to produce a unified Quality of Service (QoS) ontology This ontology must be applicable to the main scenarios currently identified such as QoS-based Web Services selection, QoS monitoring and QoS adaptation. An evaluation of existing research in the field of QoS and Service Level Agreement (SLA) ontologies is presented. Many of the authors of these works are involved in the initiative. The aim of this evaluation is to identify the weaknesses and strengths of existing ontologies in order to decide which parts of each should form the basis of a unified ontology. Current progress in the ontology engineering process is also presented.