OBJECTIVE The authors critically examined the quantitative measures of cultural competence most commonly used in medicine and in the health professions, to identify underlying assumptions about what constitutes competent practice across social and cultural diversity. METHODS A systematic review of approximately 20 years of literature listed in PubMed, the Cumulative Index of Nursing and Allied Health Literature, Social Services Abstracts, and the Educational Resources Information Center identified the most frequently used cultural competence measures, which were then thematically analyzed following a structured analytic guide. RESULTS Fifty-four instruments were identified; the 10 most widely used were analyzed closely, identifying six prominent assumptions embedded in the measures. In general, these instruments equate culture with ethnicity and race and conceptualize culture as an attribute possessed by the ethnic or racialized Other. Cultural incompetence is presumed to arise from a lack of exposure to and knowledge of the Other, and also from individual biases, prejudices, and acts of discrimination. Many instruments assume that practitioners are white and Western and that greater confidence and comfort among practitioners signify increased cultural competence. CONCLUSIONS Existing measures embed highly problematic assumptions about what constitutes cultural competence. They ignore the power relations of social inequality and assume that individual knowledge and self-confidence are sufficient for change. Developing measures that assess cultural humility and/or assess actual practice are needed if educators in the health professions and health professionals are to move forward in efforts to understand, teach, practice, and evaluate cultural competence.