This study aims to compare, on the basis of Russian and French, the morphological expression of the internal structure of eventualities (in the Davidsonian sense of this term) in Slavic languages and their external delimitation ("taxis") expressed by inflectional morphology in Romance languages. The study concentrates on the lexical level. It shows that the internal structuring, which consists of three stages (process, natural term, state), is relative to the ontology of eventualities. By contrast, the external boundaries (starting point and end point) are relative to the duration of the eventuality, independently of its internal structure. These two types of structuring, internal and external, are articulated differently in Slavic languages and in Germanic and Romance languages. In Slavic, the internal structure is grammaticalized while the external delimitation is lexicalized. In Germanic languages and in Romance, however, the internal structure is lexicalized, while the external structure is grammaticalized. Our analysis also focuses on the typologically determined distinction between the referential structuring of eventualities and the semantic structuring of Aktionsarts, as well as the interaction between Aktionsart and aspect, and the relationship between telicity and its morphological (either lexical or grammatical) shape.