|Abstract:||A wide variety of phonological phenomena appear to be scalar in nature. These include chain shifts, 'bounce-back' effects, and 'cline-effects'. Although many such scales appear to be grounded in some phonetically substantial dimension, there are strongly scalar phenomena that cannot be economically expressed in terms of grounded scales. On these grounds, this paper argues that constraints in the grammar may make reference to abstract scales which act as a form of representational metadata (not replacing representations, but defining structural relationships between then). A formalization of such scales is offered, as well as a proposal regarding the class of constraints that make reference to these scales. It is argued, based upon a survey of scalar phenomena from a variety of languages, that a grammar without this mechanism, or a mechanism of equal formal power, is descriptively inadequate. Furthermore, a historical and synchronic analysis of the tone sandhi systems and coordinate compounding constructions of Western Hmongic languages shows how abstract scales allow the insightful analysis of unnatural and opaque phonological alternations that are relatively intractable under more conventional theoretical assumptions. These findings are important to the continuing debate regarding naturalness and abstraction in phonology.