A study was conducted to gain insight into the question answering abilities of good and poor readers by comparing how well they answered questions when their prior knowledge was at two different levels (high, low) and in four different states. These states of prior knowledge consisted of the ways in which answers to the questions were stored in the reader's memory before a text was read--accurately, inaccurately, incompletely, or not at all. Subjects were 56 fifth-grade students of equivalent intelligence but varying in reading ability and level of prior knowledge. To identify the prior knowledge level of the students, an experimenter-designed assessment instrument--intended to tap all information from the passages that was required to answer experimenter-designed comprehension questions--was administered. The subjects read passages that had been prepared on two different topics and at three different levels of difficulty, and then responded to the comprehension questions concerning the passages. The results showed that the poor readers did not use a large store of background knowledge to the same advantage as did the good readers. The poor readers' prior knowledge seemed to help only in answering verbatim and paraphrased questions when the answers were already stored accurately. The poor readers were not using their prior knowledge for in-depth processing of text or for completing a framework with new information. (FL)