Leadership is widely recognized as an essential driver of organizational performance and improvement, but little is known about its role in driving quality of early childhood programs and outcomes for staff and children. In launching the Early Care and Education Leadership Study (ExCELS), the U.S. Department of Health and Human Services' Office of Planning, Research, and Evaluation (OPRE) seeks to fill the definitional and measurement gaps to help the early childhood field understand how effective leaders can improve quality experiences for children in early care and education (ECE) settings. The study team will identify leadership constructs, map out and test their associations to outcomes, and develop a short-form instrument to measure ECE leadership in center-based settings.