Ontology Engineering is currently advancing from a pure research topic to real applications. This state of the art is emphasized by the wide range of European projects with major industry involvement and, in the same time, by the evergrowing interest of small and medium size enterprizes asking for consultancy in this domain. A core requirement in all of these efforts is, however, the availability of proved and tested methods which allow an efficient engineering of high-quality ontologies, be that by reuse, new building or automatic extraction methods. Several elaborated methodologies, which aid the development of ontologies for particular application requirements, emerged in the last decades. Nevertheless, in order for ontologies to be built and deployed at a large scale, beyond the boundaries of the academic community, one needs not only technologies and tools to assist the engineering process, but also means to estimate and control its overall costs. These issues are addressed only marginally by current engineering approaches though their importance is well recognized in the community. Different approaches exist to estimate costs for engineering processes. We will present the parametric cost estimation model ONTOCOM and its alignment with the DILIGENT engineering methodology. Based on the resulting cost function some analytical evaluations of application scenarios for the DILIGENT model are provided.
