This research examined the formation, change and sustainment of institutional identity over a period of almost three decades under one leader at a public research institution in the southwest. This qualitative case study used constant comparative analysis with interview transcripts and convocation address transcripts to examine the change in institutional identity at this one public research institution. The focus of this study was to understand how the institutional identity formed, changed or remained sustained at one public institution for three decades under the same leader. A second focus of this study was to understand the institutional identity of this public institution in the context of the institution's historical purpose. Two types of themes regarding sustaining institutional identity were presented in this research. The first type of theme was a foundational one, meaning the theme was discovered in both sets of data sources at the same level of consistency. The two foundational themes in this study were: "Institutional Mission and Identity" and "Core Values." The second type of theme discovered in this research is called a flexible theme. Flexible themes were ones found throughout the course of the study but in varying levels in each of the data sources depending on the decade. The flexible themes found were: "Academic Quality," "Change in Culture," "Community Partnerships," "Higher Education Landscape" and "Infrastructure Quality." The research revealed that though previous research on institutional identity had been conducted within private or religious institution types, institutional identity can be formed and sustained at a public research university over a long period of time. It was recommended that upper level higher education administrators reflect on the clarity of institutional identity at the institution they serve, embrace institutional identity as it aligns with the purpose of the institution, include institutional identity knowledge in hiring decisions for institutions, consider institutional identity in strategy planning and communication, create educational opportunities for understanding institutional identity in higher education leadership conference programs and conduct intentional understanding of the institutional identity based on the historical mission, purpose and type of institution. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]