Educators commonly recommend that children born during the summer months, especially boys, be given an extra year to mature before entering kindergarten so that they will not suffer from the academic disadvantages of being among the youngest children in a class. Terms such as "academic red-shirting" and "graying of the kindergarten" have been invented to describe the practice and effects of holding children back from kindergarten. This Digest asserts that research cited in support of delayed entrance, however, is meager and somewhat contradictory. Results of a study comparing a group of summer-born children who delayed school entrance to a group who entered kindergarten on time (matched for intelligence) indicated that boys with summer birth dates tended to be advantaged academically by postponing entrance; the advantage was greatest in reading. The Digest asserts that such small-scale studies need to be replicated before educators can make informed recommendations about optimum kindergarten entrance age. The Digest notes that affluent parents tend to hold out their summer-born children more often than do low socioeconomic status parents, causing children at academic risk from poverty factors to face the additional hurdle of being compared to advantaged children who are 12 to 15 months older. The Digest concludes by noting that academic achievement is only one piece of the school entrance age puzzle, and that blanket recommendations to hold back one group of children only serve to change who will be part of the youngest group. The Digest recommends that educators and parents consider the individual child when making entrance age decisions. (EV)