This dissertation explored the relationship between Emotional-Social Intelligence (ESI) and student leadership practices among college student leaders. Additionally, analyses were conducted to determine if these constructs related to student performance within a university-sponsored, cocurricular, four-year leadership development program (Program). The study of Emotional Intelligences and its relationship to effective leadership is evident in the literature; however, little if any research has applied this concept to student leadership practices and more specifically, student performance within a leadership development program. Eighty-Three students enrolled in the Program completed the Emotional Quotient Inventory, EQ-i (Bar-On, 1997) and the Student Leadership Practices Inventory, S-LPI (Kouzes & Posner, 2005). Additionally, the Program director completed a modified 360-degree assessment to help measure the extent that participants’ self-reported scores (EQ-i and S-LPI) were supported by their performance within the Program. Pearson r correlations found that many S-LPI subscales positively correlated, either moderately or strongly, with the following EQ-i variables: overall ESI, the Intrapersonal subscale, Self-Actualization, the Interpersonal subscale, Social Responsibility, Empathy, Stress Tolerance, the Adaptability subscale, Problem Solving, the General Mood subscale and Optimism. Among leadership practices, Modeling the Way, Enabling Others to Act, and Inspiring a Shared Vision correlated most frequently with the ESI construct. Top Performers in the Program scored significantly higher than did other performance groups (Middle and Bottom Performers) in 11 out of the 21 ESI variables. Additionally, Top and Middle Performers scored significantly higher than did Bottom Performers in the following S-LPI subscales: Modeling the Way, Inspiring a Shared Vision, and Challenging the Process. In terms of demographic differences and ESI, significant differences were identified with gender, age, GPA, race, year in the Program (cohorts), and mother’s education level. And within student leadership practices, significant differences were only identified with GPA, race, and father’s education level. Within four of the five S-LPI subscales, participants with fathers who had 2- and 4-year degrees scored significantly higher than participants with fathers who did not have a college degree. Implications for practitioners of student leadership development programs are outlined, particularly the provision of student leadership development opportunities. Recommendations for future research are discussed.