To determine whether the Posner task, which measures the speed at which information is retrieved from the long term memory, improves prediction of reading comprehension, 121 students from reading and study skills and teacher education courses were administered the Posner task and listening comprehension, reading comprehension, and SAT verbal tests. For the Posner task, students were asked to identify pairs of letters as identical, related, or dissimilar. A comparison of test results indicated that findings from the Posner task cannot be generalized to all reading tests. The retrieval speed measure appeared to add to the prediction of reading comprehension only when the reading measure was closely matched to that of listening comprehension. The varying correlations among the reading comprehension measures suggested that different reading tests tapped different verbal and visual processes. While the Posner task was not always useful in improving prediction of reading comprehension, it does contribute to current efforts to design and develop information processing measurements related to reading comprehension. (Tables of correlation results are included.) (MM)