Purpose: To understand complex expository text, readers often engage in metacognitive comprehension monitoring. Metacognitive monitoring is assumed to rely on basic cognitive abilities (working memory updating, short-term memory, verbal intelligence). These abilities decrease in later adulthood. We thus compared younger and older adults in their comprehension monitoring and examined whether performance differences are mediated by differences in cognitive abilities. Methods: Younger (n = 101; 18-29 years) and older adults (n = 108; 60-75 years) completed an inconsistency task to capture metacognitive comprehension monitoring, two tests of working memory updating (one based on a semantic and one on a formal criterion), a short-term memory test, and an indicator of verbal intelligence. Results: Older adults reported fewer inconsistencies than younger adults ([beta] = -0.174, p = 0.009). These differences were mediated by differences in working memory updating, short-term memory, and verbal intelligence. Working memory updating based on a semantic criterion, in contrast to working memory updating based on a formal criterion, was especially related to performance differences in the inconsistency task ([beta] = 0.299). Conclusion: The present study extends previous results on the role of basic cognitive abilities for explaining differences between age groups in metacognitive comprehension monitoring in younger compared to older adults.