For English as a foreign language (EFL) graduate students in STEM, with the need to publish in an international journal comes the double burden of developing general English language skills and discipline-specific writing skills. To help these students effectively, discipline-specific scientific writing (SW) instruction is necessary but has been scarce in Asian contexts. This study investigates how discipline-specific SW courses were developed for graduate students at a Korean science and engineering university, if the courses were successfully implemented, and what could be done to improve the offering of such courses. The study uses a mixed methods research design, informed by the research paradigm of pragmatism. The dataset used in the present study includes interviews, questionnaire surveys, and performance measurement. Interviews were conducted with six language and five content professors and nine teaching assistants, and 42 students involved in the development and offering of the SW courses. A purposive sampling approach was used in selecting interviewees. In addition, two types of questionnaire surveys were conducted among the students who had taken the courses: 225 participated in the university survey and 312 in the program survey. In addition, a pretest and posttest were given to measure students' improvement in their SW performances. For data analysis, text analysis and descriptive statistics were used. The results show that the courses were well received by all those involved. Students expressed appreciation for their instructor's individual attention and feedback on their writing. Moreover, students' posttest scores showed substantial improvement. On the other hand, the study raises such issues as difficulties in collaboration between the language and content professors and the need to enhance the course's relevance to students' major fields. The study concludes by offering suggestions on how to improve the interdisciplinary aspect of SW courses for STEM students and by providing a recommended model of interdisciplinary collaboration among language and content professors and teaching assistants.