The purpose of the ExCELS compendium is to describe information on measures of leadership relevant to early childhood settings. Further, the compendium identifies what information exists and what information is needed to better understand leadership and its influence in ECE settings. For the ExCELS project, the compendium will inform the development and testing of a new measure of ECE leadership. More broadly, the compendium will provide the ECE field —including researchers, program evaluators, and leadership program or quality initiative developers—with an overview of how various related disciplines are conceptualizing and measuring leadership in ways relevant to ECE. (author abstract)