Entrance age in kindergarten has been a controversial issue as the range from the youngest to the oldest student spans up to 24 months. This range leaves a heterogeneous gap for teachers who are already differentiating for their English Language Learners, struggling students, and high achieving students. This is compounded by the fact that the research is conflicting. Some researchers argue that this difference in age creates lasting effects on students throughout their educational years. Others disagree, stating that the initial disadvantage disappears as the students' age increases. In order to determine the effect of age, the current study utilizes archival data from 641 students in Corona Norco Unified School District. These students were surveyed according to their California Standards Test Scores (CSTs) in the area of language arts from grades two through six. It was hypothesized that the younger students would have higher test scores than the older students. In addition, family background characteristics would contribute to entrance age. The data were analyzed for frequencies, means, and linear regression. The analysis uncovered factors that were similar and different from current research, and background characteristics did not determine entrance in the current data set. A positive correlation existed between age and achievement for second and third grade. However, this achievement gap narrowed by third grade. This shows a diminishing effect. Parent education, family income levels, and gender factors contributed to student achievement. As parent education levels were particularly significant, additional analyses were performed. These analyses found that students whose parents had higher levels of education (college and above) had significant gains with age in second grade. Students with lower levels of parent education did not have any significant gains with age. As age matters for a short time and creates a diminishing factor, it can be concluded that it is not as significant as other background factors, especially parent education, socioeconomic status, and student gender. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]