The monitoring of meaning and the correction of miscues that fail to make sense are a hallmark of a proficient reader. Much of the research, however, has focused on the reading of fictional, narrative texts. In contrast, this research examines the monitoring and response behaviours of 35 proficient fourth grade readers (nine and 10 years of age) to their miscues on a complex, scientific text. Specifically, reader reactions to their miscues that did and did not disrupt meaning were analysed. Regardless of their impact on meaning, the majority of miscues were ignored. Readers failed to correct, failed to attempt to correct, the majority of their meaning disrupting miscues. This behaviour may be due to an emphasis on reading rate in many classrooms, a failure to explicitly teach older students monitoring and correcting strategies, and the complexity of the text.