Categorial Grammar at a Cross-Roads Johan van Benthem Abstract: Categorial grammars are driven by substructural logics. These are fragments of modal logics for the structures the grammar deals with. We discuss modal languages as a means of access to families of relevant structures: formal languages, type hierarchies, relation algebras c.q. arrow models, and even geometrical vector spaces. Keywords: categorial grammar, Lambek Calculus, ternary models, types, parsing, modal logic