This paper presents the Constraint Language for Lambda Structures (CLLS), a first-order language for semantic underspecification that conservatively extends dominance constraints. It is interpreted over lambda structures, tree-like structures that encode lambda-terms. Based on CLLS, we present an underspecified, uniform analysis of scope, ellipsis, anaphora, and their interactions. CLLS solves a variable capturing problem that is omnipresent in scope underspecification and can be processed efficiently.