Effects of illustrations on learning authentic textbook materials were studied among 10-year-old elementary school children of high and low intellectual ability. Experiment 1 showed that the presence of illustrations improved learning of illustrated text content, but not that of nonillustrated text content. Comprehension scores were improved by the presence of illustrations for high-ability children, but not for low-ability children. In Experiment 2, children's eye movements were measured during learning of illustrated textbook passages to study how children divide their attention between text and illustrations. The results suggest that learning is heavily driven by the text and that children inspect illustrations only minimally. High-ability students were more strategic in processing in the sense that they spent relatively more time on pertinent segments of text and illustrations. It is concluded that the learning of illustrated science textbook materials involves requirements that may be more readily met by more intellectually capable students. Copyright 1999 Academic Press.