Measures of cognitive intelligence such as Intelligence Quotient (IQ) have long been utilized as gatekeeper measures for leadership placement within organizations. Universities and Colleges have created leadership degree programs which are often almost exclusively measures of a student's cognitive ability. The degrees conferred are often the "gatekeeper" measures for entry into a leadership position within an organization. However, leaders with analogous educational and professional backgrounds may experience different levels of success even when facing quite similar situations. Why is this? The answer may be found within a fairly new field of study known as Emotional Intelligence (EI). The purpose of this study was to explore the degree of association between EI and school performance. The first question addressed within this study dealt the degree of association between a middle school principal's Total EI score and school success. Secondly, this study attempted to focus on the specific elements of a principal's EI (Area and Branch scores) and the degree of association that those elements might have with school success. This research project rendered valuable information which indicated that various components of a middle school principal's EI level is closely related to school success. With this information school systems and school personnel may begin to recruit and promote throughout the principal ranks those principals that demonstrate high levels of EI. Furthermore, training programs may be developed to enhance EI in public middle school principals in an effort to support higher levels of school success. Ultimately, this research indicated that the association between EI and school success could not be ignored and that additional study is strongly indicated. (Contains 9 figures and 2 tables.) [Ph.D. Dissertation, Capella University.]