The present study employed a difference-in-difference approach to determine the impact of a technologically enhanced diagnostic and formative assessment system implemented in one US state in kindergarten through third grade on school-level end-of-year third-grade reading test scores and percentage of students receiving special education services. Data were obtained for 795 elementary schools that implemented the assessment system in a staggered progression across multiple years. The analysis estimated the effect of the assessment system on the entire third-grade sample, and by selected demographic characteristics. Results showed no effect of the assessment system on average end-of-year reading scores or school-level percentage of students receiving special education services. Follow-up models including time and fidelity information also obtained null results overall. Given the null, schools should consider modifications to the ways they obtain, manage, and use assessment data.