After earning a master's degree from Princeton University and serving as President of the Chinese Students Christian Association, Yen returned to China in 1921 to head national mass literacy campaigns under the Chinese National YMCA. In 1923, Yen and leading intellectuals such as Liang Qichao, Hu Shih, and Tao Xingzhi formed the National Association of Mass Education Movements (MEM). The MEM organized campaigns across the country which coordinated volunteer teachers, local leaders, and any available location in order to attract students who could not pay high tuitions. Among the volunteer teachers was Mao Zedong. These campaigns attracted more than five million students and served as a model for even more widespread schools.
