Content validation and cultural adaptation are necessary to interpret evidence from psychological assessment instruments imported across cultures.

The cross-cultural use of psychological assessment instruments-especially those developed in one cultural context and applied in another-raises critical concerns about content validity and the potential for misleading interpretations drawn from measures derived from those instruments. This article argues that without rigorous cultural adaptation and content validation, psychometric indices and interpretations derived from imported instruments used in cross-cultural assessment may be biased and thus misleading. We first clarify the multidimensional and continuous nature of culture and review psychometric principles, emphasizing the conditionality of evidence across cultural contexts. A central focus is on content validity-the extent to which an instrument accurately reflects the behaviors, attitudes, and emotions it purports to measure within a new cultural setting-and its influence on validity. We outline best-practice steps for evaluating and enhancing content validity in culturally adapted instruments, including translation, expert review, qualitative interviews, psychometric evaluation, and final modification of the instrument based on the reviews and qualitative and psychometric data from the new population. To assess current adherence to these practices, we reviewed 401 published articles from six high-impact psychology journals during the first six months of 2025. Results revealed that nearly all studies failed to implement comprehensive content validation procedures. Out of the 54 articles that reported using assessment instruments imported from a different country or culture, only three fully adhered to recommended strategies. These findings underscore the ethical and scientific importance of rigorous cultural adaptation in cross-cultural assessment. Limitations of the review and directions for future research are discussed.