To explore the possibility that the tendency to cluster during free recall reflects organizational processes that are central to the attainment of certain reading skills, 32 mentally handicapped subjects were asked to recall 20 words from four conceptual categories on four consecutive trials. For one group the words were presented in random order on all four trials. For the second group, the words were presented in categories on two trials and randomly on two trials. The subjects in each group were further divided into above and below median reading comprehension subgroups. The major findings were that organized word presentation increased clustering on subsequent nonorganized trials, and that the above median reading comprehension group clustered significantly more than the below median group. (Author)