This article addresses the derivational relationship between attributive (nominal) and predicative (verbal) possessives marked by the poss sign in American Sign Language. Though traditionally classified as a possessive pronoun, a collection of morphological, syntactic, and semantic patterns is presented here as evidence that poss instead displays the distributional characteristics of a verbal predicate in the language. Classifying poss as a verbal predicate of possession explains its presence in predicative possessives and allows its attributive use to be derived from this underlying verbal structure as an instance of a prenominal reduced relative clause modifier. These base structures and their interaction with other components of the predicative and attributive domains explain the documented properties of attributive and predicative poss possessives, including, crucially, the sometimes divergent behaviors of these two possessive constructions.