When individuals read or listen to prose they try to understand what it means. This is quite obvious. However, the cognitive mechanisms that participate in prose comprehension are far from obvious. Even simple stories involve com plexities that have stymied many cognitive scientists. Why is prose comprehen sion so difficult to study? Perhaps because comprehension is guided by so many domains of knowledge. Perhaps because some critical mysteries of prose comprehension reside between the lines-in the mind of the comprehender. Ten years ago very few psychologists were willing to dig beyond the surface of explicit code in their studies of discourse processing. Tacit knowledge, world knowledge, inferences, and expectations were slippery notions that experimental psychologists managed to circumvent rather than understand. In many scientific circles it was taboo to investigate mechanisms and phenomena that are not directly governed by the physical stimulus. Fortunately, times have changed. Cognitive scientists are now vigorously exploring the puzzles of comprehension that lie beyond the word. The study of discourse processing is currently growing at a frenetic pace."