Two off-line and on-line reading tasks investigated the real-time comprehension of doubly quantified sentences with sentential negation interaction. The results showed that perceivers experienced processing difficulty in assigning inverse-scope interpretations to the sentences with double operators, not only when such sentences appeared in isolation, but also when the preceding context supported the inverse-scope interpretation and when the quantified sentences with negative operators was unambiguously inverse scope. We conclude that the cost of assigning inverse scope arises from the greater syntactic complexity of the inverse-scope representation, as a structure-driven model of the human sentence processing mechanism and referential context hypothesis would predict.