A balanced assessment system is vital to the instructional process in all schools. This system includes both formative and summative assessment measures. Both assessments provide data that can inform curriculum design and the instructional process. The purpose of this study was to examine the predicative validity of formative diagnostic and benchmark assessments to determine which can be used to accurately predict students' performance on an end of year state mandated reading assessment. This quantitative study used correlation coefficients, analysis of variance, regression equations, and Tukey to analyze diagnostic and benchmark results of 1367 third grade students to determine if diagnostic and benchmark scores could accurately predict student passage on an end of year summative reading assessment in third grade. The study also sought to determine if kindergarten reading readiness could be used to predict student reading achievement in third grade. The findings of the investigation revealed a relationship between diagnostic and benchmark assessment results and students' scores on state assessments. The study also revealed that while gender is not a factor in determining students' reading success by the end of third grade, the school's accountability rating is directly related to students' ability to read proficiently. [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.]