|Abstract:||This article proposes a model of variation and change within the Optimality Theory framework. Previous attempts to account for variation in Optimality Theory have a common flaw; they fail to include a link to the external world where demographic factors such as gender, age, style, register, and social class play a material role in linguistic behavior. I propose Vestige Theory as a means of using Optimality Theoretic architecture to license the influence of language external factors. Vestige Theory claims that language change is always the result of constraint demotion and that the demotion of a constraint leaves behind a vestige of itself. This vestige constraint is a kind of output-output constraint. It differs from the “true” constraint that is demoted as part of language change. As an output-output constraint, a vestige constraint has the link to the outside world (i.e. to external factors) that previous models have failed to incorporate.