This paper investigates the integration of definite determiner phrases (DPs) as a function of their contextual salience, which is reflected in the degree of dependency on prior information. DPs depend on previously established discourse referents or introduce a new, independent discourse referent. This paper presents a formal model that explains how discourse referents are represented in the language system and what kind of mechanisms are implemented during DP interpretation. Experimental data from an event-related potential study are discussed that demonstrate how definite DPs are integrated in real-time processing. The data provide evidence for two distinct mechanisms – Specify R and Establish Independent File Card – and substantiate a model that includes various processes and constraints at the level of discourse representation.