This paper argues that subject-verb agreement comes in at least three different categories: D-agreement, phi-agreement, and n-agreement. Each of these agreement categories is associated with predictable distributional properties that are derived from its categorial properties. D-agreement (as instantiated in Standard Arabic) associates with C and establishes an agreement relation with the discourse subject; phi-agreement (as instantiated in English) associates with T and establishes an agreement relation with the grammatical subject; and n-agreement (as instantiated in Tarifyt Berber and Halkomelem Salish) associates with v and establishes an agreement relation with the thematic subject. It is shown that the category of agreement determines its behaviour in the context of Subject A'-movement.