A profession has been defined as a calling requiring specialized knowledge and intensive academic preparation. At the University of Missouri-Columbia, specialized knowledge and intensive academic preparation have been the hallmarks of its program since its inception in 1839. The University of Missouri-Columbia (MU) is the flagship and land-grant institution of the four-campus University of Missouri system. This article describes the professionalization of MU's teacher preparation program called Teacher Development Program (TDP) and presents a discussion of the four design principles adopted by the faculty, which serve as the foundation of the program: (1) organizing programs around the problems of practice; (2) creating opportunities for inquiry and reflection; (3) utilizing developmental approaches to performance assessment; and (4) focusing on what educators need to value, know, and be able to do. This article also discusses Teacher Development Program's organization which consists of four phases. These phases provide checkpoints for the major assessments and provide the opportunity to remediate and assist students that have not met phase criteria. Both diversity and use of new learning technologies are overarching themes that are integrated throughout each phase of the program.