This qualitative study examined professors' experiences in teaching online courses in an English-medium graduate program at a Japanese university. Based on Andragogy Theory, data included in-depth, semi-structured interviews with six professors who were faculty in a graduate program in Sport for Development. Synchronous online and follow-up e-mail interviews were conducted. A constant comparative method was used to interpret the data and identify themes. The recurrent themes were: (a) "positive experiences in teaching online sport for development courses," (b) "learning how to become effective teachers in an English-medium program," and (c) "the importance of faculty professional development." To better support Japanese professors' online teaching, this study encourages academic departments, administrators, and faculty to better design professional development activities that enhance the quality of online education and the use of English as the medium of instruction.