This article is focused on the major features of the Culture Care Diversity and Universality theory as a central contributing theory to advance transcultural nursing knowledge and to use the findings in teaching, research, practice, and consultation. It remains one of the oldest, most holistic, and most comprehensive theories to generate knowledge of diverse and similar cultures worldwide. The theory has been a powerful means to discover largely unknown knowledge in nursing and the health fields. It provides a new mode to assure culturally competent, safe, and congruent transcultural nursing care. The purpose, goal, assumptive premises, ethnonursing research method, criteria, and some findings are highlighted.