The power of Web Service (WS) technology lies in the fact that it establishes a common, vendor-neutral platform for integrating distributed computing applications, in intranets as well as the Internet at large. Semantic Web Services (SWSs) promise to provide solutions to the challenges associated with automated discovery, dynamic composition, enactment, and other tasks associated with managing and using service-based systems. One of the barriers to a wider adoption of SWS technology is the lack of tools for creating SWS specifications. OWL-S is one of the major SWS description languages. This paper presents an OWL-S Editor, whose objective is to allow easy, intuitive OWL-S service development and to provide a variety of special-purpose capabilities to facilitate SWS design. The editor is implemented as a plugin to the OWL ontology editor, and is being developed as open-source software.