This chapter proposes a mechanism for mapping domain ontologies to metamodels by a direct mechanism; this proposal is necessary because there is no formal mechanism for obtaining requirements in model driven engineering. Specifically, here the authors propose the use of a domain ontology as the main input for defining metamodels. They define a point in common between domain ontologies and metamodels to apply a method of direct conversion between domain ontology and the metamodel. At the end of the chapter, the authors present a real case study in which they use the technique described and the conclusions of the investigation.