DOLCE (a Descriptive Ontology for Linguistic and Cognitive Engineering) is the first module of the WonderWeb Foundational Ontologies Library. DOLCE is an axiomatic ontology (thus, it is a heavy- weight ontology, in contrast to light-weight ontologies, which mainly define taxonomic structures). DOLCE is an ontology of particulars. A basic choice made in DOLCE is the so-called multiplicative approach: different entities can be co-located in the same space-time. The ontology is developed with respect to the OntoClean methodology (Guarino and Welty, 2002). OntoClean is a methodology for validating the ontological adequacy of taxonomic relationships. DOLCE is axiomatized in a very expressive modal logic, but from it several simplified sub-ontologies are isolated. Such sub- ontologies are: DOLCE-LITE which includes 80 classes, 80 properties, 24 axioms represented in OWL; DOLCE-Lite-Plus which contains additional extensions in direction to Plans, Information Objects, Semiotics, Temporal relations, Social notions, etc. DOLCE UltraLite is a very light version of DOLCE, which uses friendly names and comments for classes and properties, has simple restrictions for classes. All these ontologies can be seen as lightweight versions of the fully axiomitized ontology.