Emerging adulthood is a unique and distinct period demographically, subjectively, and in terms of identity exploration in developed and developing countries. This study aimed to investigate emerging adults’ moral thinking and communication competencies, and their differences by socio-demographic factors (i.e., gender, religious affiliation, college major, educational stages), in Taiwan, the USA, and the UK, as well as compare similarities/common trends and diversities between the three groups. We modified and utilized the MTC-II scale, including two dilemma stories relating to an individual and societal moral dilemma, to assess 743 valid sample participants. We found that females in the Taiwan group scored highest on the MTC-II scale across the three samples, whereas religious affiliation differentiated the USA and the UK groups. We also noted differences in scores relating to the two stories and associated moral levels. These findings are interpreted as a foundation for future research and educational practice.