Research that bears on the issue of school entry policies is summarized in this report. The focus is on the age children should be to enter kindergarten and the potential benefits of delaying school entry for all or some children. The research reviewed uses three methodologies: (1) comparing outcomes for children who have delayed entry by a year with children who entered school when they were eligible; (2) comparing children in the same grade who have different birth dates; and (3) comparing children who are the same age but in different grades, as well as children who are a year apart in age but in the same grade. Findings suggest that studies using the first method are inconclusive because accommodations are not made for the selection factors associated with the decision to hold a child out of school. Findings from the other two methods suggest that relatively older children have a modest academic advantage over younger children in the first few grades of school, but that advantage typically disappears. There was no evidence suggesting that younger children gained less than older children from early school experience, and some evidence suggested that school experience produced greater gains on most cognitive dimensions. Generally, the findings reviewed provide more support for early educational experience to promote academic competencies than for waiting for children to be older when they enter school. The author suggests that the focus should be more on making schools ready for children than on making children ready for school.