Forty children each from nursery school, first grade, and third grade participated in a study of the use of symbolic mediators in the control of overt behavior of children with internal and external locus of control. Each child participated in three different verbal control tasks: a push-button task, a pounding-board task, and a serial-recall task. Effects for grade level, sex, locus of control, and instructional condition (no verbalization, forced verbalization, and free condition) were also examined. Results indicated that performance increased as grade level increased. Further, forced verbalization aided in performance of sequential tasks but hindered performance on the push-button task. Progression from overt to covert self-verbalizations was related both to chronological age and to proficiency at a task. There was no significant evidence that children with internal locus of control spontaneously verbalized more than did externals or that they performed better on the verbal control tasks. (Author/AA)