Moral foundations theory has been a generative framework in moral psychology in the last 2 decades. Here, we revisit the theory and develop a new measurement tool, the Moral Foundations Questionnaire-2 (MFQ-2), based on data from 25 populations. We demonstrate empirically that equality and proportionality are distinct moral foundations while retaining the other four existing foundations of care, loyalty, authority, and purity. Three studies were conducted to develop the MFQ-2 and to examine how the nomological network of moral foundations varies across 25 populations. Study 1 (N = 3,360, five populations) specified a refined top-down approach for measurement of moral foundations. Study 2 (N = 3,902, 19 populations) used a variety of methods (e.g., factor analysis, exploratory structural equations model, network psychometrics, alignment measurement equivalence) to provide evidence that the MFQ-2 fares well in terms of reliability and validity across cultural contexts. We also examined population-level, religious, ideological, and gender differences using the new measure. Study 3 (N = 1,410, three populations) provided evidence for convergent validity of the MFQ-2 scores, expanded the nomological network of the six moral foundations, and demonstrated the improved predictive power of the measure compared with the original MFQ. Importantly, our results showed how the nomological network of moral foundations varied across cultural contexts: consistent with a pluralistic view of morality, different foundations were influential in the network of moral foundations depending on cultural context. These studies sharpen the theoretical and methodological resolution of moral foundations theory and provide the field of moral psychology a more accurate instrument for investigating the many ways that moral conflicts and divisions are shaping the modern world. (PsycInfo Database Record (c) 2023 APA, all rights reserved).