Our research addressed an increase of unethical practices in professional settings identified in the literature, and this increase coincides with a shift in U.S. culture from principle-based ethics to one trending toward moral relativism. We discovered many programs lack comprehensiveness to deal with the complexities of culture in graduate education. The purpose of this instrumental case study was to explore and develop a conceptual framework for a comprehensive teaching model targeting graduate-level educators, administrators, and educational boards across disciplines. Data were collected over 13 years from a doctoral professional ethics course at a private, faith-based university in South Texas. Using a Design Based Research process following Reeves’ (2006) guidelines, we developed a multi-disciplinary graduate theoretical teaching model for ethics: Comprehensive Professional Ethics Teaching Model (CPET model), grounded in our data analysis and findings. Recommendations include implementing and testing the efficacy of the CPET model in subsequent studies.