Given the objections and controversies surrounding the “diversity, equity, inclusion, and belonging” (DEIB) criteria for organizations and institutions, it seems important to disentangle the ambiguity of this concept. This chapter analyzes it through the lens of Personalist Philosophy. This philosophy turns around the notion of “person,” which denotes dignity and entails human-wholeness, substantial unity of body and mind, the uniqueness of each person, and the relevance of personal growth. Under this perspective, four categories of diversity are identified. One is based on ontological considerations (a sexed being), which embraces the whole person, body, and mind. A second is derived from individual relatively stable internal features. A third refers to diversities based on personal ties and communitarian belonging, such as family, religious, ethnic, sociocultural, socioeconomic, and geopolitical diversities. The fourth category refers to diverse personal developments, including personal endowments acquired over time, which bring about differences in education, character development, hobbies, professional expertise, and organizational situations. The recognition of this diversity involves, first, the recognition of the universal human dignity and innate rights inherent to each person, and the moral imperative treating of every person with good will and benevolence. Second, recognizing diversity by showing respect and awareness of minorities and vulnerable groups and giving help to specific groups in accordance with their respective identity. Third, leading organizations and institutions with practical wisdom and a sense of community, building up such a community framed by the common good, solidarity, and subsidiarity, and promoting personal growth and sense of belonging through appropriate participation and support.