Multi-Tiered System of Support (MTSS) is a framework within which schools provide evidence-based instruction and support to all students aligned with their identified needs. When social and emotional learning (SEL) is embedded within MTSS, it offers a foundation to support learning in ways that address the full array of student need. In 2016, the Orange County Department of Education, the Butte County Office of Education, and SWIFT Education Center with support from the California State Department of Education launched a large scale state-wide effort to implement MTSS with embedded SEL. This effort offered districts and schools across the state the opportunity to build their systems to support the whole child (CA SUMS Annual Report, 2018). This brief presents a study of a sample of schools from this state-wide program in relation to student academic outcomes. This study offers important information for the field related to educational innovation. Specifically, this systematic study demonstrated positive outcomes for students in English Language Arts (ELA) and Math when compared with matched controls, thus offering promising evidence of efficacy for implementation of SEL-MTSS. Students benefit when school leaders have (1) a strong philosophical foundation on which to build, (2) access to high-quality professional learning and technical assistance, (3) an evidence-based framework, and (4) a clear focus on the mechanics of how to implement SEL-MTSS.