Positive changes or transformations have been the subject of study within spiritual traditions as well as humanistic and transpersonal psychology. The aim of the current study is to understand the process of transformation among Moslems in Indonesia, who follow spiritual practices, to achieve the nafs al-muṭma ínnah [tranquil self]. Ten participants in Yogyakarta province were involved in this study. They were recruited using nafs al-muṭmaʾinnah scale developed by the authors. In-depth interviews of both the participants and their significant others were (...) conducted. To analyse the data, an interpretative phenomenological analysis was employed. Five themes emerged from the data, including deviation from the basis of religious environment, spiritual discipline, transformative experiences, new characters and a continuous process. We conclude that participants experience spiritual-religious transformation and achieve the state of nafs al-muṭma ínnah [tranquil self]. The process of transformation occurs gradually after a sudden experience, and it continuously happens throughout the course of life. Three factors contribute to the transformation, including the role of predisposition, the role of a spiritual guide and the role of spiritual experiences.Contribution: As the study of spiritual-religious transformation is mainly conducted within a Judea-Christian tradition, this study significantly contributes to the literature by providing spiritual-religious transformation from an Islamic-Sufi perspective. (shrink)