During reading or listening, language comprehenders construct a mental representation of the objects and events mentioned. This model is augmented and modified incrementally as the discourse unfolds. In this paper we focus on the interpretation of bare quantifiers, that is, expressions such as 'two', to investigate the processes underlying the construction and modification of the discourse model. Bare quantifiers are temporarily ambiguous when sentences are processed incrementally. For instance, in 'Three ships were in the port. Two...', 'two' can either refer to a subset of the set just mentioned (e.g.,'two of the three ships'), a different set of the entities mentioned (e.g., 'two other ships'), or a set of different entities (e.g., 'two people'). Data from previous studies, and a current completion study, suggest that the subset interpretation is preferred over the establishment of a different set. The current study aimed to investigate ERP correlates of quantifier interpretation and their timing. Quantifiers that unambiguously signaled the establishment of a new referent elicited a late positive component (900-1500 ms), which we interpret as a Late Positive Complex, related to the difficulty involved in context updating. An additional 500-700 ms positivity was elicited only in a subset of readers, suggesting that there are individual differences in quantifier interpretation and the timing thereof.