This article provides an overview and synthesis of the current literature on metacognition and comprehension monitoring among adult readers. It is organized around three major research questions: (1) How do adults conceptualize their own comprehension-fostering and comprehension-monitoring activities? (2) How effectively do adults evaluate and regulate their ongoing efforts to understand? (3) How successfully do adults assess the final products of their comprehension efforts? Cutting across these broad issues are questions concerning metacognitive differences as a function of reading ability, academic success, domain expertise, developmental level, and task variables. The research reveals that adults' conceptions of how they comprehend and how they monitor their comprehension are quite variable. In general, those who have more expertise, who are better readers, and who are more successful students seem to have greater awareness and control of their own cognitive activities while reading. The research also reveals that adults evaluate and regulate their ongoing efforts to understand, although there is considerable room for improvement in these skills. Finally, the research shows that adults are remarkably unsuccessful at assessing how well they have comprehended a text and whether or not they are ready to take a test on the material. The article closes with a discussion of recent intervention efforts aimed at enhancing the metacognitive skills of adult readers.