In this article, we describe a researcher-practitioner partnership (RPP) that used a networked improvement community (NIC) approach to translate social-psychological interventions into educational practices to enhance student motivation and learning. Specifically, we highlight one of our first collaborative projects to develop and scale up an intervention to teach middle school students about adopting a growth mindset (Dweck, 2006) to address our practitioners' concern that many of their students lacked the belief that they could learn. Using Plan-Do-Study-Act cycles, we show how we (a) successfully adapted a previously used growth mindset intervention designed for college students into a computer app appropriate for middle school students, (b) embedded using the app in different middle school contexts to promote growth mindset thinking, and (c) linked students' growth mindset thinking to improved academic performance. We also discuss how this work was conducted as part of a networked improvement community sponsored by the Carnegie Foundation for the Advancement of Teaching called the Student Agency Improvement Community.