In a study of memory use in language comprehension, 84 second grade, 54 sixth grade, and 54 college students produced elaborations on sentences. In a context elaboration, task students put sentences in different contexts, and, in a causal inferencing task, they inferred alternative reasons for events. Language understanding was measured by the number of essential ideas recalled from an expository text. Results indicate that elaborative thinking is one basic component of language understanding, and suggest a hierarchical model of that understanding. On the first level of the model are causal and descriptive elaborations, with great variation even at this basic level. The next level of understanding is the causal level, where in addition to temporal sequence of events, the whole chain of events becomes reasonable. At the highest level is the ability to infer and be aware of causal alternatives. In this study, poor text understanders were able to make all kinds of elaborations, but fewer than their classmates. This means that rather than focusing on how to elaborate and infer, instruction should concentrate on broadening the repertoire of elaborations and inferences. Simple instructional methods have been successful in accomplishing this objective. A brief bibliography is included. (MSE)