The enormous need for well engineered ontologies is growing rapidly, as the need for ontologies is increasing in many application areas. Due to the central role ontologies are playing, the World Wide Web Consortium (W3C) developed the Web Ontology Language (OWL) as a language to author ontologies. For an ontology language to be easily understood by domain experts it must be close to the natural language they speak and the ‘logic’ they use. Also, it should have a graphical notation to enable simple and conceptual modeling. The expressive, methodological, and graphical capabilities of Object-Role Modeling (ORM) make it a good candidate for use in ontology engineering. In this book, we (i) map the ORM constructs to OWL 2 using SROIQ Description Logic and, on the other hand, we (ii) extend the ORM notation to cover all OWL 2 constructs not currently covered by ORM. By doing so, we combine the strengths of both ORM and the W3C-recommended Web Ontology Language (OWL). This creates a framework that allows one to engineer OWL ontologies graphically using ORM. This book will provide the needed knowledge for interested field persons of ontology engineering.