The Halpern Critical Thinking Assessment (HCTA) is a reliable measure of critical thinking that has been validated with numerous qualitatively different samples and measures of academic success (Halpern, 2010a). This paper presents several cross-national applications of the assessment, and recent work to expand the validation of the HCTA with real-world outcomes of critical thinking (e.g., contracting a sexual transmitted infection because you did not wear a condom). The real-world outcomes (RWO) inventory measures behavior in a wide range of domains, such as education, health, finance, and interpersonal relationships. Study 1 examined whether scores on the HCTA predicted real-world outcomes in three qualitatively different samples in the United States. Study 2 used the HCTA to assess the effectiveness of an online critical thinking course, and whether the HCTA predicted real-world outcomes in Ireland. Study 3 describes preliminary research involving the translation quality of the RWO (into Spanish and Portuguese) and explored differences in behaviors in the two countries. Overall, the HCTA is a useful tool for assessing critical thinking and predicts real-world outcomes of critical thinking. Cross-national implications and applications are discussed.