Part One of this book is based on ethnographic fieldwork conducted by the author during 1970-72 on a local branch of the Muhammadiyah in the town of Kotagede, a suburb of Yogyakarta, Indonesia. This work, first published in 1983, observed that the Muhammadiyah social and educational movement had reformed traditional Javanese Islam into a vital living faith and adapted Muslim life to modernity. The author was one of the first scholars who had noted that there was continuing Islamization in Indonesia and predicted its progress in the future. Part Two is based on the author's three decades of follow-up visits to the Kotagede from the 1970s to 2010. During this period, the Muhammadiyah movement made enormous advancements, enough to to make the town known as a "Muhammadiyah town".