The purpose of this study was to develop a grounded theory of the process of mission-based leadership development over the career lifecycle of faculty, staff, and administration in Catholic higher education. Using constructivist grounded theory, interviews were conducted at three Catholic higher education institutions with professionals at various stages of their career to identify commonalities between their experiences and embrace of mission-based leadership. The generated Theory of Mission-based Leadership Development for Catholic Higher Education Professionals includes three identified phases which occur within a communal context and are founded upon three foundational elements: "mission comprehension and integration", "ongoing leadership exploration, development, and trait formation", and "community engagement, peer support, and culture." The study's generated theory may assist Catholic higher education institutions in developing ongoing formation programs for professionals to actively engage the institution's mission in their role within the campus community. [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.]