This chapter discusses the thought of Juan Luis Vives, who was a prominent voice in sixteenth-century debates on language and learning between humanists and scholastics. The chapter shows that, like Valla, Vives presents himself as a defender of common language and common sense. The notion of “common” turns out to be ambiguous. As the chapter makes clear, in most contexts the common language is Latin, but in Vives’s attacks on what he considered the linguistic and dialectical aberrations of his scholastic opponents, common language could also mean the usage and conventions of any linguistic community. Though his critique focuses on the Latin of his opponents, the point is sometimes phrased in terms that go beyond this particular language. This critique of scholastic language is part of a wider reform of language and learning that Vives thinks is necessary. The chapter therefore examines his views on the origins of language, its functions and purposes, and the role he assigns to the topics (loci) in thinking and argumentation. It is suggested that for Vives the topics form a grid through which we structure our thought and speech.