This quantitative correlational study examined the relationship between the overall and sub-component scores (operations and algebraic thinking, measurement and data, and geometry) of the i-Ready and TNReady assessments for fourth-grade students in a Title 1 elementary school in Middle Tennessee. The study included 109 students with complete data on the i-Ready Spring Diagnostic Assessment and the TNReady State Standardized Assessment during the 2018-2019 school year. The study initially aimed to analyze subcomponent levels of the assessments. However, discrepancies in the categorization and reporting of the TNReady state academic standards required a shift to examine the correlation between i-Ready and TNReady overall and percent proficient mathematics scores. The findings revealed a very strong positive correlation between i-Ready diagnostic scores and TNReady mathematics scores, r (107) = 0.88, p < 0.001, indicating that higher i-Ready scores are consistently associated with higher TNReady scores. Additionally, a very strong positive correlation was found between i-Ready percent proficient scores and TNReady percent proficient scores, r (107) = 0.89, p < 0.001, suggesting that higher iReady percent proficient scores strongly correlate with higher TNReady percent proficient scores. These results underscore i-Ready's potential as a formative assessment tool to enhance student outcomes and align with state assessment standards. [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.]