This volume is devoted to the central cases relating to the basic oppositions between subject-object and agent-patient, viz. nominative and accusative, as well as their counterparts such as ergative and absolutive. It aims at contributing to the typological investigation of these cases by providing descriptive studies of ten different languages, not only Romance and Germanic languages, but also Polish and Basque, as well as Cora, Warrwa and Ewe. These studies show that the formal devices used to mark the two nuclear cases may be quite diverse (including non-overt and 'configurational' coding), but that all the languages studied crucially display a subject-object asymmetry, even languages such as Basque and Ewe for which this had been questioned. One of the most striking subthemes to emerge from this collection is the complexity of the object-zone, both with regard to formal and functional diversity. Various studies in the volume also contribute reflections, couched mainly in broadly cognitive-functional terms, about the semantic function of the subject-object contrast and why it is so central across languages.