The purpose of this quantitative study was to examine the relationship between students' performance on the Cognitive Abilities Test (CogAT) and the fourth and fifth grade Reading and Math Achievement Tests in Ohio. The sample utilized students from a suburban school district in Northwest Ohio. Third grade CogAT scores (2006-2007 school year), 4th grade Reading and Math Ohio Achievement Test scores (2007-2008 academic year), and 5th grade Reading and Math Ohio Achievement Test scores (2008-2009 school year) were utilized in this study. Pearson Correlation was utilized to examine the relationship between the test scores. Secondly, the researcher examined whether the correlation coefficients between CogAT and fourth and fifth grade Ohio Achievement Test scores differ by CogAT performance level (below average, average, above average). Additionally, a linear regression test was utilized to determine whether the composite scores from the CogAT can predict proficiency on the fourth and fifth grade Ohio Achievement Tests in Reading and Math. The correlation coefficient on all four achievement tests indicated strong positive significant relationships between scores on each achievement test and scores on the CogAT for the entire sample (n=292), while three of four of the coefficient correlations were weak for the below average group. The average group generated the strongest correlations of the CogAT with all the OATs examined. The above average group generated moderate correlations. Predictions for future academic achievement are stronger with the above average and average groups, while weaker for the below average group. In general, students who score approximately 93-95 on the CogAT in 3rd grade are likely to achieve a proficient level on the 4th and 5th grade OAT for Reading and Math. The range of CogAT scores necessary to predict accelerated and advanced levels increases greatly. In addition, higher CogAT scores were necessary to achieve accelerated or advanced for Reading (4th and 5th) in contrast to the Math (4th and 5th). Overall, the results indicate the CogAT is significantly related to the fourth and fifth grade Reading and Math achievement tests, which indicates cognitive ability, and can be used to predict future academic achievement, while supporting the importance of making data-driven decisions. Professional development is a major policy application that is necessary to understand CogAT score reports and provide teachers with applicable, practical, and meaningful methods for teaching to a diverse group of students. Future study opportunities could determine if a relationship exists between teacher interventions implemented in the classroom and future academic success on achievement tests, while another study could focus on the impact of teacher performance on student success on future achievement tests. Additional studies could be conducted to determine the correlations between the CogAT and other states achievement tests to see if a significant relationship exists. [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.]