This paper presents a developmental study of the effects of item rehearsal on children's short term memory. Two experiments are discussed. The first, involving second and sixth grade children, concerned the relationship between item retrieval ability and rehearsal strategies in item recall. The design of the experiment involved varying the visual availability of items prior to recall and varying instructions for active rehearsal. Active rehearsal instructions significantly improved the recall of second grade children, most significantly in the item-available condition. Item availability did not significantly affect the performance of the sixth grade children. These results suggest that item retrieval may not be an important component of active rehearsal. The second experiment concerned the relationship between rehearsal activity and the organizational structure of the recall material. Subjects were third and sixth grade children. This experiment involved sorting words into semantically related, story related, or random groups. Item availability was also varied. Results from this study suggest that active rehearsal may assist in the development of an organizational structure, and that once this structure is attained or developed by the subject, recall is constant regardless of age of subject. Results from both experiments emphasize the importance of rehearsal strategies in short term memory processing. (BD)