Social-emotional learning has become a popular focus within the school setting, which is aimed at fostering the well-being of the "whole child." These programs have encapsulated an array of different character strengths, skills, and aptitudes which nurture interpersonal relationships and promote effective social-behavioral competencies. One of the emerging areas of emphasis in social-emotional processes, is emotional intelligence (EI), a construct broadly referring to self- and other- emotional awareness that guides decision making and thinking. EI has predominated the adult literature but is only beginning to have a large focus within youth populations. Of those studies which exist in children and adolescents, EI has been associated with a number of strengths-based outcomes (e.g., increased life satisfaction, stronger peer relationships, decreased pathology and negative behaviors), and is considered a driving force for children's future well-being and multi-dimensional functioning. Despite the emphasis on EI in both popular culture and scholarly pursuit, issues in conceptualization and measurement have prompted the need for an empirically sound and valid measure that can gauge youth's level of EI. The present study proposes a novel way of evaluating EI in children, through a teacher-report form called the Pfeiffer EI Scale. This scale was constructed in an attempt to minimize concerns with existing instrumentation and provide a rating of children's EI level that can be used in conjunction with SEL programming in schools. Items on the Pfeiffer EI Scale are based upon measurable and observable characteristics of EI, which span across ability-based, trait-based, and mixed models of EI. Previous analysis (through exploratory factor analysis) of this scale revealed strong internal reliability and an underlying three-factor solution of the scale, which measures Positive Expression of Emotions, Negative Expression of Emotions, and Understanding and Managing Emotions. This dissertation serves as a continuation of the preliminary psychometric analysis of the Pfeiffer EI Scale. To demonstrate factorial validity of the measure, confirmatory factor analysis was performed. A three-factor solution was verified from this analysis after re-specifying the model and comparing it against a uni-dimensional structure; however, fewer items were retained. With careful consideration to underlying theory and conceptualization of EI, a total of 15 items were dropped from the original 47-item scale due to low factor loading, high conceptual overlap with other items, and high modification index values. The remaining 32-item total scale and individual factors maintained excellent internal consistency reliability. In an attempt to establish convergent validity with existing measures, the Pfeiffer EI Scale was compared to existing student-completed EI instruments (Mayer-Salovey-Caruso Emotional Intelligence Test – Youth Version; Emotional-Quotient Inventory, Youth Version, and Schutte Self-Report Emotional Intelligence Scale). No statistically meaningful relationship was found between teacher-reported EI and ability-based EI. The total score of the Pfeiffer EI Scale and Understanding and Managing of Emotions factor was weakly related to the Stress Management domain and total score of mixed-model EI. Additionally, no relationship was found between teacher-reported EI and trait-based EI. No relationship was found between the teacher-reported EI and life satisfaction or affect, suggesting minimal concurrent validity. A mild positive relationship was found between grade point average and the Positive Expression of Emotions factor, Understanding and Managing of Emotions factor, and Total EI score. There was a negative, weak relationship between the Understanding and Managing of Emotions factor and disciplinary action, indicating that students with greater disciplinary offenses had decreased EI scores. Females performed stronger than males on most factors and the total Pfeiffer EI score. No differences were found across ethnic or racial groups on teacher-reported EI. Individuals with higher socio-economic status did receive higher scores on the Negative Expression of Emotions factor compared to those with lower socio-economic status. The only meaningful difference across ages was between 11- and 15-year-olds on the Positive Expression of Emotions factor, suggesting that EI did not differ much across age bands. Overall, despite having solid internal consistency reliability, the results provide minimal support for the convergent and concurrent validity of the Pfeiffer EI Scale. However, included within this dissertation are proposed rationale for factors impacting validity, including the "subjectivity" of the emotional experience, informant discrepancies commonly found between other-rater forms, and the over-extension of the concept of EI. Despite the contradictory findings to many hypotheses, this study provides a unique perspective on how EI may be measured within youth populations and inform clinical and assessment practices. Limitations of the current work and future directions of study are also discussed.