This paper draws upon previous studies in the field of modality to explore the pragmatics of prescriptive and performative verbs used to express different degrees of obligation in EU legislation. The study aims at demonstrating that modality plays a key role in the institutional language of the European Union, as it reveals the different pragmatic purposes of its legislative text types and mediates the communicative interaction between the legal authority (European institutions) and the addressee (Member States). Attention is also devoted to the concept of interculturality vis-à-vis the different ways obligation is conveyed in English and Italian official documents.