Agreement plays a central role in modern generative grammar. The present collection brings together contributions from experts on various aspects of agreement systems in the world’s languages in an attempt to formulate formal and substantive universals in this domain. All the papers contained here focus on the formalization of the mechanisms of agreement and on the relationship between case and agreement. All the papers propose solutions by seriously examining cross-linguistic data from the usual Germanic and Romance languages to Lummi, Greek, Hindi, Turkish and other Turkic languages, Japanese, Tsez, Masaai, Russian, Arabic, Basque, Warlpiri, Kaltakungu, and Bantu.