Decades of research have emphasized the need for engaging, accessible ways to help students learn fundamental mathematical concepts. Research also shows that teacher beliefs about teaching and learning have an outsized influence on the quality and effectiveness of curricular interventions. This article reports results of an independent evaluation of the i3 implementation of SunBay Digital Mathematics, a middle-school math intervention, and examines the program's impacts on both student progress and teachers' beliefs about math instruction. Prior studies have demonstrated the efficacy of SunBay Math for students of varied levels of prior achievement. This independent evaluation included a randomized controlled trial in 60 Florida middle schools during the 2015-16 school year and a mixed-methods implementation study. No impact on student achievement was observed overall; however, the evaluation did reveal positive impacts on teachers' classroom practices and beliefs about the use of technology in math instruction. Inadequate implementation of instructional units and lack of impact on teachers for targeted beliefs about math instruction likely contributed to lack of overall program effects.