Hoogervorst, Jan A.P.Dietz, Jan L.G.2017-08-282017-08-282008Originating from quite different fields of theory and practice, the terms "Enterprise Ontology" and "Enterprise Architecture" currently belong to the standard vocabulary of those professionals who are concerned with (re)designing and (re)engineering enterprises, thereby exploiting modern information and communication technologies for innovating products and services as well as for optimizing operational performance. Because of the inherent characteristics of modern enterprises, often operating within networks of cooperating enterprises, the task of these professionals can rightly be characterized as having to master unprecedented high complexity. The statement, put forward in the paper, that the current notion of Enterprise Architecture does not offer satisfactory help and thus need to evolve into an effective conceptual tool, is clarified in a historical context. In order to let Enterprise Architecture become a sensible, effective notion, complementary to Enterprise Ontology, it is proposed to define it conceptually as normative restriction of design freedom, and operationally as a coherent and consistent set of design principles. The new, evolved notion of Enterprise Architecture is clarified and illustrated using a case example.enText/Journal Article10.18417/emisa.3.1.11866-3621