Research and experience has led ISM to hypothesize that the School Head’s well-being significantly relates to school outcomes. ISM recently conducted a study of School Heads to extend our knowledge of executive leadership and investigate the relationship among our Tier 1 markers of the ISM Stability Markers®, School Heads’ characteristics and experience, and their well-being. In upcoming I&P issues, we will publish the more nuanced results of this study. The purpose of this article is to re-introduce our approach to the measurement of executive leadership and describe the general results and conclusions. Great leaders can transform a school and take it to new heights, whereas poor leaders can cause great challenges for schools. We have long asserted that, as the executive leader, your “style” does not seem to account for the differences in organizational performance. Nonetheless, you are a critical component of a school’s ability to deliver its mission with excellence. If it is not style, then what are the critical aspects of executive leaders that separate the best leaders from the rest?