The aims of this study are to compare the conversion career of Catholic Religious Sisters and Buddhist Nuns, for further understanding complex conversion phenomena and promoting interreligious understanding and dialogue. To get these aims, the concept of conversion is clarified first. Then the theories and issues, Catholic and Buddhist ideas of conversion, and the history of female religious lives are understood. All are the base of this study. In-depth interviews are conducted to get ten conversion stories (from five Catholic religious sisters and five Buddhist nuns). Conversion phenomena are understood and analyzed according to Phenomenology of Religion and Constant Comparative Method in Ground Theory. From the history and theories of conversion research, Lewis Rambo’s holistic theory is used to organize and analyze the data collected. Henri Gooren’s conversion career theory is employed as analytic skeleton. Dale Cannon’s Six Ways of Being Religious is used to compare the ways co-researchers use to go to Ultimate Reality. The main results of this study are: The Interdisciplinary approach of conversion theory is often used by modern scholars. This study supports most people convert gradually (80% in this study) in their adolescent or early adult. After their baptism or taking refuge, they continue their conversion. The Macrocontext of this study is around 1949. Many religious people flee away Mainland China and preach actively in Taiwan afterwards. Most of the co-researchers’ family believe in Popular Religion or Lay Buddhism. They live happily and have enough income to support their family. They contact new religions through social network. Sisters Group study Catechism before baptism, while Buddhist nuns Group take refuge when ritual of taking refuge is conduct in temples. After initial conversion, Sisters Group feel called by Jesus and decide to live religious lives, while most Buddhist nuns Group don’t feel called and go to convent many years later. 80％ of their parents oppose their decision, because they don’t want them to suffer and to be lonely when old. After communication, their parents agree. But 20% of their parents don’t agree until they stay in convent or receive upasaṃpqnna. Sisters Group are trained according Catholic Cannon Law, while Buddhist nuns Group vary. After upasaṃpqnna, they become Masters of Buddhist. Being a perpetual member, co-researchers live in a community to improve their spiritual lives and work for their community and society. From the ways of being religious, they contact new religions by way of Reasoned Inquiry and Devotion in Growth Period. Sisters Group are more intellectual in Quest Period for studying Catechism. After baptism, Sister Group is more in Right Action ways, while Buddhist nuns Group vary. In Training Period, they receive the methods of spiritual training according to the traditions. In Devotion Period, they practice in community with other members and do the jobs assigned by
