To understand a text, a reader must engage in three important cognitive activities--recognition, comprehension, and memory. Based on this premise, two experiments were conducted with children to assess individual and developmental differences in speed of word recognition and how these differences related to performance on a variety of memory tasks. One unexpected finding was that although rapidity of word recognition increased sharply and continuously from grade one to grade nine, development was independent of this increase. An important implication of the two experiments is that developmental gains in rapidity of word recognition may have no necessary relation to memory improvement, but that individual differences may go hand in hand with differences among the same individuals in memory skills. Two other experiments with school-aged children revealed that certain effects studied extensively in sentence verification (the negation and comparator effects) replicated well in sentence completion, that stable differences among individual children did exist, and that the differences probably derived from variation in the efficiency with which different children executed elementary cognitive processes. (The full report of the first two experiments is appended.) (HOD)