Data from a large suburban school district in Tennessee (N = 910) were used to examine the effects of the Kindergarten Readiness program as measured by third grade End of Year (EOY) benchmark performance assessments in reading and math. The groups of students studied included kindergarteners with summer birthdays ("SK"), kindergarteners with fall and spring birthdays ("K"), students who participated in Kindergarten Readiness Classes ("KR"), and "redshirted" students ("RS"). The "KR" group had a statistically significant higher mean of reading and math scores when compared to the "SK" group and a statistically significant higher mean of math scores when compared to the "K" group. When there are concerns that young children with summer birthdays may not be ready to begin school, this research study supports the need to allow parents to make the decision to redshirt their children, enroll them in Kindergarten Readiness Classes, or enroll them in regular kindergarten classes.