This cross-sectional survey questionnaire study explores the Petrides Model of Trait Emotional Intelligence (TEI) of school principals in the Commonwealth of Pennsylvania, employing the Trait Emotional Intelligence Questionnaire (TEIQue). This research study explored statistical differences in TEI components (Global Score, factor scores, and facet scores) for demographic factors such as gender, experience level, education level, geography, locale, and school level for 155 participating school principals representing 161 schools. More importantly, this study attempted to examine whether any correlation existed between TEI components and student achievement and growth outcomes. Noteworthy findings indicated that female school principals, on average, exhibit higher emotional intelligence than their male counterparts, aligning with existing literature emphasizing females' enhanced interpersonal skills. Intriguingly, novice principals with five or fewer years of experience attained significantly higher TEI scores than their intermediate and experienced counterparts, challenging the expectation that experience positively affects TEI. Educational levels show mixed results, with master's degree holders generally outscoring their doctoral counterparts. Geographic and locale-based analyses reveal higher TEI scores among eastern region and rural principals, presenting novel insights into potential regional disparities. TEI and student achievement correlations indicate significant relationships with PSSA English Language Arts scores, mainly linked to Emotion Perception and Self-Motivation. However, no conclusive correlation could be determined regarding student growth, suggesting a need for nuanced understanding or potential scaling discrepancies in growth assessments. This study contributes to existing literature by addressing gaps in research methodology and focusing on the specific context of the Commonwealth of Pennsylvania. Recommendations for future research emphasize the need for more empirical studies, exploring generalizability, perceived versus externally evaluated TEI, qualitative analyses, and longitudinal investigations. The findings underscore the pivotal role of emotionality in a school leader's ability to create an environment conducive to student achievement and growth. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]