The purpose of this study was to investigate whether or not a child's chronological age at the onset of kindergarten influences foundational literacy skills and if there is an impact on long-term reading achievement. Research indicates that there are several factors that influence school readiness and the foundational literacy skills that must be developed in order for a child to learn to read (Cox, 2016; Department of Health and Human Services and The National Institute for Literacy, 2008; Fountas & Pinnell, 2017; Hinojosa, 2016; Richardson, 2106). Prior to this study, very little research had been done on the relationship between chronological age at the onset of kindergarten and reading achievement. Most children enter kindergarten at the age of five (National Center for Educational Statistics, 2014), but some parents elect to delay the start of kindergarten until age six (Datar, 2006; Hughes, 2016). In this quantitative study, data was collected and analyzed to determine if younger students are less prepared to read than their older peers. Data was also analyzed to conclude if chronological age impacts reading achievement by third grade. The study focused on answering the following three research questions: RQ1. Is there a relationship between chronological age and the foundational literacy skills of kindergarten students identified with delayed literacy development? Hypothesis 1. Kindergarten students with birthdays at the younger end of their class (May, June, and July) display characteristics of delayed literacy development on early literacy assessments and qualify for reading intervention services at higher rates than their chronologically older peers. RQ2. Is there a relationship between chronological age and reading achievement of third-grade students who read below grade level expectations? Hypothesis 2. Third grade students with birthdays at the younger end of their class (May, June, and July) display characteristics of struggling readers on reading achievement assessments and qualify for reading intervention services at higher rates than their chronologically older peers. RQ3. Do gender, race, and poverty impact reading achievement? Hypothesis 3a. Gender (male or female) has an impact on reading achievement. More boys qualify for reading intervention services than girls. Hypothesis 3b. Race (white or not white) has an impact on reading achievement. A higher percentage of non-white students qualify for reading intervention services than white students. Hypothesis 3c. Poverty (qualifying for free or reduced price lunch or not) has an impact on reading achievement. Greater percentages of students who are eligible to receive free or reduced price lunch qualify for reading intervention services than students who do not qualify for free or reduced-price lunch. The researcher analyzed the chronological ages of 3,896 kindergartners in a large suburban school district in the St. Louis area during a three-year span. Descriptive statistics and binary logistic regression analysis were run in SPSS on the kindergarten data to determine if a difference existed between the independent subgroups (coded student birthdays) on the dependent variable of qualifying for reading intervention or not. The results showed that a statistically significant percentage of younger students with birthdates in May, June, and July qualified for reading intervention than their older peers. To study the long-term effects of chronological age on reading achievement, birthdates from 4,430 third graders who were enrolled in the same large suburban school district during the three-year span were analyzed. Descriptive statistics and binary logistic regression analysis were run in SPSS on the third-grade data to determine if a difference existed between the independent subgroups (coded student birthdays) on the dependent variable (qualifies for reading intervention vs. doesn't qualify). The results showed that while greater percentages of younger students qualified for reading intervention, the difference was not statistically significant. Descriptive statistics and binary logistic regression analysis were run in SPSS to estimate the effects of gender, race, and poverty on reading achievement. The results concluded that students who qualified for free or reduced-price lunch were three times more likely to need reading intervention than their more affluent peers. While gender was a factor in kindergarten (more boys qualified for reading intervention than girls) by third grade, the difference was not statistically significant. Race did not increase the probability that a student would qualify for reading intervention. The impacts of these results were discussed in detail and recommendations for further studies were described. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]