Adapting a comprehensive psychological assessment tool such as the Intelligence and Development Scales - 2 (IDS-2) to diverse cultural contexts requires a careful balance between ensuring cross-national comparability and achieving local validity for each language version. This contribution outlines the rigorous procedures underlying the international adaptations of the IDS-2, highlighting methodological standards as well as collaborative practices. We will present how central coordination of test adaptations ensures consistency in the test materials and the psychometric quality while allowing necessary modifications of the test material to account for cultural and linguistic specificities. Given the comprehensive nature of the IDS-2 we can demonstrate how the involvement of local experts from the developmental domains assessed (e.g., psychomotor skills, social-emotional development, scholastic abilities) is essential for developing culturally appropriate test materials. At the same time, adapting intelligence measures across cultures requires a focus on high comparability to enable factorial stability across language versions for generalizable interpretations of results. We also illustrate how standardization data can be used not only to establish reliable local norms but also to support secondary analyses and research. This approach fosters further research into an internationally adapted instrument and enables both continuous refinement of the measure and basic research on the assessed constructs. Applying this dual approach—combining rigorous quality assurance with openness to empirical scrutiny—to the international adaptations of the IDS-2 ensures that the IDS-2 remain both scientifically robust and practically useful across language versions. In sum, we present how the adaptation of the IDS-2 exemplifies best practice in cross-cultural test development by integrating methodological precision, interdisciplinary expertise, and international collaboration. These efforts enhance the clinical and educational utility of assessments like the IDS-2 and ensure their ongoing alignment with the latest scientific knowledge and practical needs.