This chapter studies the Spanish grammatical relations (subjects, objects, prepositional objects, adjuntcts) paying special attention to the convergences and differences with the Italian counterparts; it offers an introduction to the historiography of grammatical relations in Spanish and Italian and gives an overview to the main grammatical relations of Spanish (formal means of expression, semantics, and operational tests). The chapter appears in a Contrastive Spagnish-Italian Grammar resulting from an international research project (the University of Salamanca Press co-publishes the volume).