The 21-item Depression, Anxiety, and Stress Scale (DASS-21) is a common instrument for measuring dimensions of emotional distress. In the present research, we tested across five studies (N = 2,096) whether the number of items could be reduced while maintaining high reliability and validity. Specifically, Item Response Theory and Confirmatory Factor Analysis reduced the number of items to 12, which we named Mini-DASS. Our findings revealed the Mini-DASS is as psychometrically robust as the DASS-21. Multigroup Confirmatory Factor Analysis established its invariance across gender and three countries (Brazil, UK, and USA). The Mini-DASS and the DASS-21 demonstrated similar correlation patterns with other well-being measures and the five moral foundations. Notably, we observed negative correlations between depression, anxiety, stress, and the authority and loyalty foundations. In conclusion, the Mini-DASS is a parsimonious, reliable, and valid instrument for measuring depression, anxiety, and stress.