This study investigated (1) the difference, if any, between the achievement in reading readiness of younger kindergarten children (4 years 9 months to 5 years 1 month upon school entrance) and older children (5 years 5 months to 5 years 8 months at entrance), (2) whether kindergarten positively affects the reading readiness achievement of children regardless of age, and (3) whether younger kindergarten children with training equal the level of reading readiness attained by the older kindergarten children with training. The 39 middle class children were measured with the Lee-Clark Reading Readiness Test after 5 weeks of school and again after 90 days. Results indicated (1) that there was a positive relationship between reading readiness achievement and kindergarten training in younger children, and (2) that without kindergarten training, maturation plays a large part in affecting children's reading readiness achievement. It was concluded that early exposure to formal school training is desirable for all children, and a reevaluation and revision of available reading readiness tests was suggested. (DR)