Improvement and action-oriented research approaches make iterative testing to learn about systems and adaptive change a central practice. As the need to develop the field's capacity to improve grows, so does the need to develop leaders' capacity for leading and conducting iterative cycles of testing. The present study reveals how EdD candidates learn to investigate and specify problems and aims, develop the capacity to lead, and conduct iterative cycles of testing in schools and school districts. We draw on the implementation of core learning activities in one Educational Leadership Doctoral Program employing improvement science as a signature methodology. Findings suggest shifting candidate orientations, growth in the capacity to engage in iterative cycles for improvement of problem definition and actionable steps, and the ability to garner collegial engagement in improvement and iterative testing. Implications highlight the importance of designing and structuring learning activities beyond those that exist in traditional research methods courses to ensure adequate candidate preparation.