Integrating twenty-first century competencies into the curriculum has become an important issue for education reform worldwide. This study examines and compares twenty-first century competencies demonstrated in mother tongue curriculum standards in China, the United States and Finland. It identifies key similarities and significant differences among them. It shows that the Finnish Curriculum has a more balanced distribution of twenty-first century competencies. While communication and critical thinking are stressed in all three, critical thinking is prioritised in the American Curriculum. In addition to communication and critical thinking, the Chinese Curriculum emphasises citizenship based on national identity, metacognitive strategies and aesthetics. The American Curriculum focuses on information and ICT literacy, and the Finnish Curriculum highlights personal and social responsibility concerning cultural awareness and citizenship. The significant differences between these three Curricula are related to the countries' tradition of curriculum theories -- the Chinese integrate Western theories and the Confucian tradition, the American follow the Anglo-American curriculum and the Finnish have roots in "Bildung-Didaktik." Curriculum objectives should take into consideration both subject knowledge and skills and the student as a whole person. Additionally, different curriculum traditions should be considered and learned during the curriculum design process.