Ontology-Based Evaluation and Design of Domain-Specific Visual Modeling Languages Giancarlo Guizzardi, Luís Ferreira Pires and Marten van Sinderen CTIT, University of Twente, Enschede, The Netherlands guizzard@cs.utwente.nl, pires@cs.utwente.nl, sinderen@ctit.utwente.nl Introduction In recent years, increasing attention has been paid to the development of domain-specific visual modeling languages (DSVLs). It is believed that these languages can lead to an increase in productivity in the modeling ac- tivity and contribute to the production of models that are more flexible, re- usable and easier to maintain than models produced by using general- purpose modeling languages (Tolvanen et al, 2004). However, in order to be effective, a DSVL must be defined taking into account the needs of its client users. From their perspective, the use of the language should be sat- isfactory in the following terms: (i) it should easy for a user of the lan- guage to communicate, understand and reason with the produced models (comprehensibility appropriateness); (ii) The language should be truthful to the domain in reality that it is supposed to represent (domain appropri- ateness). In this article, we present an ontology-based method for the evaluation and (re)design of DSVLs that reinforces properties (i) and (ii) above. We start by presenting the different elements of languages design, namely, syntax, semantics and pragmatics. After that, we discuss the subject of formal ontologies and its relation to each of these elements and present the proposed method. Finally, we illustrate this method with the design of a visual modeling language in the domain of genealogy. Elements of Language Design According to (Morris, 1938) a language comprises three parts: syntax, se- mantics and pragmatics. Syntax is devoted to “the formal relation of signs to one another”. In order to communicate, agents must agree on a common communication language. This fixes the sets of signs that can be ex-