This paper presents an analysis of quantifier and wh-operator scope in terms of a lexicalized theory of quantifier storage, within the framework of Head-Driven Phrase Structure Grammar. The proposed analysis provides an alternative to the derivational approach wherein quantifier scope is determined at a separate level of representation via movement, and shows how scope of quantifiers and wh-phrases (fronted or in situ) can be handled in a unified way in a constraint-based grammar. Lexicalization of quantifier storage offers an account of scope facts in raising and unbounded dependency constructions which have been problematic in an earlier constraint-based approach to quantifier scope.