A study assessed the effects of text structure and prior knowledge about its content on comprehension and recall of text by fourth and eighth grade students. Three groups, each with 15 students, were tested at each grade level. Subjects in the prior knowledge group heard and mastered a passage on one day and then heard, freely recalled, and answered probe questions about a target passage on the next day. The prior knowledge passage and target passage were written so that information in the former was related to information in subordinate levels of the latter. An unrelated knowledge group heard and mastered a passage unrelated to the target materials on one day and performed the same tasks as the prior knowledge group on the next day. A control group participated only in the target passage tasks. The results showed that both the accessibility (free recall) and the availability (probe questions) of information by the fourth grade subjects were affected by prior knowledge. These effects were not present, however, with the eighth grade subjects. The difference between age groups is consistent with the notion that children become more text bound in their comprehension as they move through school. (Author/FL)