nternational organizations (e.g., FAO1 , WHO2 , etc.) are increasingly expressing the need for multilingual ontologies for di®erent purposes, e.g., ontology-based multilingual machine translation, multilingual informa- tion retrieval. However, most of the ontologies built so far have mainly English or another natural language as basis. Since multilingual ontology building is a very ex- pensive and time-consuming undertaking, we propose methods for guiding users in the localization of ontolo- gies, and provide tools for supporting the process. The main contributions of this paper are: i) the descrip- tion of a generic Ontology Localization Activity and a methodology for guiding in the localization of ontolo- gies; ii) the description of a tool built according to the guidelines proposed for an automatic localization of on- tologies; and iii) a set of experiments used to evaluate the methodological and technological aspects of the On- tology Localization Activity.