Five groups of children were tested, and their test performances were compared. Experimental group one (X-1) consisted of 105 children who had attended a yearlong Preschool Readiness Center program. Experimental group two (X-2) consisted of 93 children who had attended a summer Head Start program. Control groups one and two (C-1 and C-2) consisted of 79 low income children with no preschool training. Control group three (C-3) consisted of 59 middle income children with no preschool experience. All preschool children were tested upon entry into their particular program by means of the Peabody Picture Vocabulary Test, the Preschool Inventory, and the California Test of Personality. All children were tested upon entry into the first grade by means of the above three measures plus the Metropolitan Readiness Test. In May 1968, during the end of their first-grade year, all children were administered the Metropolitan Achievement Test (MAT). A comparison of these results showed that upon entry into the first grade, group X-1 performed the best of all groups on the four measures, with group C-3 second best. Group C-3 scored significantly better than all other groups on the MAT, group X-1 not performing significantly better than X-2, C-1, and C-2. Thus, group X-1's initial superior performance was not sustained over the first year of school. It was discovered that children whose parents did not participate in the programs demonstrated the poorest test performances. (WD)