Indonesia, with the world's largest Muslim population, has a number of Muslim organizations. Two of the most mainstreams, Nahdlatul Ulama (Awakening of ulama [religious scholars], hereafter NU) and Muhammadiyah (followers of Muhammad), were born during the colonial period and have continued to develop to the present day. These two organizations contrast in their organizational structure. The organizational structure of the two groups is contrasting: the NU spread through the ulama's personal connections, while the Muhammadiyah has expanded nationwide through a series of organizational activities. In recent decades, the NU has attracted the attention of researchers for its political ties, while the Muhammadiyah, which has continued to be a solid player in the field of substantive educational and social spheres, has been rather neglected. This study focuses on the early Muhammadiyah, which has not been explored in previous studies, and examines its development in relation to the pergerakan (movement) groups in which bumiputra (natives, Indonesians) began to assert their rights. Hitherto, pergerakan studies mainly used colonial documents, however now we have access to internal documents of the Muhammadiyah and the contemporary Dutch newspapers. By listening to the "voices of the Muslims themselves" in these materials, this study aims to describe the organization-building activities of the Muhammadiyah.