The purpose of this mixed methods, longitudinal Improvement Science study was to examine the conditions that influence teacher capacity to engage in continuous improvement using data to guide curriculum and instructional changes. This study took place during the global COVID-19 pandemic. We Can Do It Academy, a pseudonym, was a designated priority school and one of the lowest performing schools in New York State. English Language Arts and math teachers (N = 7) in grades five through eight worked in grade-level PLCs using data for problem exploration, problem-solving, and solution testing with a goal of improving student learning. The principal focused on changing the micro-culture at WCDIA and engaging cultural carriers. Teachers differentiated students based on academic outcomes into three focus groups, using Plan-Do-Study-Act cycles and Professional Learning Communities to focus on data reflective of instruction and student skills. The key attributes of principal leadership that supported continuous improvement included being intentional, creating a psychologically safe space for change, establishing norms for discussion, designing opportunities to incorporate teachers' voices, and promoting distributed leadership. Factors influencing teacher capacity in the use of data included meeting times, establishing norms, perceptions of readiness, creating common language, providing opportunities for feedback and co-constructing the work, working in Professional Learning Communities, using PDSA cycles, peer feedback, and use of a rubric. The final PDSA cycle saw the biggest improvement (+20.56), with mean improvements of +23.03 for ELA and +9.06 for math. Improvement varied by student achievement: average (+22.06); low (+16.30); high (+9.78). [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]