This paper reports on preliminary findings from ongoing design-based research being conducted in the fully online Master of Arts in Teacher Leadership (MTL) program at a small, Midwest public university. Researchers are using the Quality Matters (QM) and Community of Inquiry (CoI) frameworks to guide the iterative redesign of core courses in the program. Preliminary results from the redesign of one course suggest that such approach can improve student learning outcomes. Results also support the efficacy of the QM and CoI theoretical frames, and the usefulness of design-based approaches in online learning. (Contains 10 figures and 2 tables.)