Since the passage of the first Elementary and Secondary Education Act in 1965, increasing reading achievement for all students has been a focus for our nation. Unfortunately, our country still has over 30 million citizens who are illiterate (Mukherjee, 2007). One of the challenges for schools is to accurately identify students in need of early intervention in an efficient and effective manner before students participate in high stakes reading assessments. This study aimed to assist school leaders in identifying which diagnostic reading measures will best identify students at risk of not passing the Ohio Third Grade Reading Achievement Assessment. The purpose of this study was to examine the relationship of students' performance on five district diagnostic reading measurement tools--(1) KRA-L; (2) AIMS probes from second grade administration; (3) DRA literacy assessment; (4) STAR Reading Assessment from second grade; (5) standards based report card indicators--and their performance on the October administration of the Ohio Third Grade Reading Achievement Assessment. Grounded in the theoretical framework of Teale and Sulzby (1992), as supported by Gunning (2006), the study examined four research questions focusing on student literacy data. The study revealed strong relationships between each of the instruments examined and the Ohio Third Grade Reading Achievement Assessment. Pearson Correlation coefficients indicated that the STAR SS and STAR PR have the strongest relationships with the Ohio Third Grade Reading Achievement Assessment. Multiple regression results indicated the STAR PR and the AIMS best predict passage on the Ohio Third Grade Reading Achievement Assessment for the total sample. The final research question examined the predictive nature of each tool for each subgroup based upon disability, SES and race. The STAR PR was found to be the most accurate for students without disabilities, both SES groups (Low SES and Non-Low SES), as well as White students and minority students. AIMS was found to be additional predictor for minority students and students without disabilities. No tool emerged as predictive for students with disabilities. While schools need to select an instrument that best meets the needs of their population, this study clearly found strong relationships between each of the instruments examined and the Ohio Third Grade Reading Achievement Assessment. With the exception of students with disabilities, significant models were generated for each subgroup. Overall the STAR PR was shown to have the strongest relationship with the Ohio Third Grade Reading Achievement Assessment. [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.]