The study examined the relationship between secondary public school principals' emotional intelligence and school performance. The correlational study employed an explanatory sequential mixed methods model. The non-probability sample consisted of 105 secondary public school principals in Texas. The emotional intelligence characteristics of the principals were documented. Analysis of the quantitative data showed that the relationship between principals' emotional intelligence and school performance was not statistically significant. Analysis of the qualitative data resulted in two themes, namely, 1) strong interpersonal and intrapersonal skills and 2) positive leadership. The principals believed that raising school performance happens over time and that key factors related to affecting school performance include building relationships, motivation, inspiration, organizational skills, emotions (knowing one's own emotions and the emotions of others), and communication skills. The results showed that a principal's awareness of his/her emotions as well as other's emotions and how to deal with them are vital to relationship building and positive leadership. The quantitative and qualitative results were synthesized and discussed. The practical implications of the study are to develop, strengthen, and enhance a principal's emotional intelligence skills in order to become a more effective administrator. The skills can begin to be taught and developed to aspiring principals enrolled in a Master's degree program. Emotional intelligence skills can also be developed, strengthened, and enhanced through professional development opportunities like continuing education classes, staff development, and workshops. [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/en-US/products/dissertations/individuals.shtml.]