The purpose of this evaluation was to examine the impact of i-Ready Personalized Instruction on math achievement, as measured by SBA scores. We compared "striving learner" students who were assigned to use i-Ready Personalized Instruction (Treatment students) and "striving learner" students assigned to only receive i-Ready Diagnostic assessments (Comparison students). The study sample consisted of 11,034 "striving learner" students in Grades 3-6 from four school districts in California. All four districts used i-Ready Diagnostic assessments, but schools in one district assigned some students to receive the Personalized Instruction product in addition to the Diagnostic product. Striving learner students in this district assigned to both the Personalized Instruction and Diagnostic products were compared to striving learner students in the other districts who were only assigned to the Diagnostic product. Overall, this analysis presents promising evidence of i-Ready Personalized Instruction on student math achievement. This relationship between i-Ready Personalized Instruction and math achievement was strongest for students in Grades 4 and 5 and students identified as Black. Usage was also related to achievement and future studies should seek to further examine the reasons behind this variation in usage.