In 2022-23, Round Rock Independent School District in Texas rebranded the Response to Intervention (RTI) as Multi-tiered Support System (MTSS). The purpose of this report is to assess the effect of MTSS on staff data literacy, MTSS implementation, and elementary school student achievement. We used a mixed-method approach, including analysis of staff and teacher survey data, focus group interviews, and difference-in-difference models. The program made a positive impact on campus contacts' data literacy and student achievement in elementary language arts. However, the effect on student mathematics achievement was negligible. Between 2021-22 and 2022-23, teachers' perceptions of MTSS improved. [This paper was created by Round Rock ISD Research & Evaluation.]