This chapter proposes a performative theory of language standardization. Language standards are described as metalinguistic speech acts that have a metalanguage- to-language “direction of fit”, i.e. their perlocutionary effect - if any - is ultimately locutionary. Under particular “felicity conditions” (in particular sociolinguistic settings), such metalinguistic acts may raise language awareness within a community and manage to effect or inhibit language change. This performative theory calls for a corpus-driven approach to standardization that concentrates on correctives (metalinguistic speech acts of the type: “one should neither say nor write X; instead, one should say or write Y, because Z”) and permissives (“one may say or write either X or Y provided that C”). Such triplets are fairly easy to locate in texts that prescribe on language usage. Both correctives and permissives are prescriptive acts. Correctives and permissives are shown to form repertories which remain relatively stable over particular periods of time. The changes in corrective repertories bear testimony to processes or re- or de-standardization. The continuing standardization of Modern Greek is discussed as a case that exemplifies the performative theory proposed in this chapter. The notions of the ‘uniformity’ and ‘neutrality’ of a Standard are also problematized with respect to Standard Modern Greek.