The illusion of knowing is the belief that comprehension has been attained when, in fact, comprehension has failed. In the present experiment, the illusion was defined operationally as having occurred when readers who failed to find a contradiction in a text rated their comprehension of the text as high. Texts containing contradictions between adjacent sentences were presented, and readers were explicitly asked to search for contradictions. The frequency of illusions was greater when the contradictory sentences came at the end of three-paragraph texts rather than at the end of one-paragraph texts and when the contradictory information was syntactically marked as new. These results are interpreted within a framework that emphasizes that the goal of reading expository text is to establish coherence within and among sentences. In addition, the results are apparently incompatible with the notion that readers engage in active and accurate on-line monitoring of the degree to which this goal is met.