A total of 125 white children from three counties in Georgia (selected as representative of small rural and medium and large industrial urban populations) were administered a battery of tests in three phases of their schooling: (1) during the summer preceding their admission to the first grade, (2) near the end of the first grade, and (3) near the end of the third grade. The two objectives of this longitudinal testing were to describe the factorial organization of intelligence at the age levels tested and to observe changes in this organization as they occurred when the same subjects were measured repeatedly. The test battery included the Wechsler Intelligence Scale for Children, the Peabody Picture Vocabulary Test, and the Ammons Full Range Picture Vocabulary Test. Twelve factors were discovered, overall. The overlapping appearance of some factors in two or more phases confirmed the idea of the existence of stable mental factors at the preschool level. Identification of two emergent factors supported the idea that intelligence tends to differentiate with increasing age and experience. (WD)